Only a few of the articles that use Grounded Theory actually create a true theory. Instead, most of them develop a set of "theoretical categories," which are essentially the same as themes in other approaches to qualitative analysis.

So, take a look at Thematic Analysis by Braun and Clarke (2006).

I rigorously studied theory synthesis to develp a new theory in my research area: Article Optimizing Staffing, Quality, and Cost in Home Healthcare Nu...

I would strongly like to suggest you to read the following thin book:

Walker L. & Avant K. (2011) Strategies for Theory Construction in Nursing, 5th edn. Prentice Hall, New York, NJ, USA.

You will get a detailed information on your queries.

The following papers may further help:

• Díaz Andrade, A. (2009) Interpretive Research Aiming at Theory Building: Adopting and Adapting the Case Study Design, The Qualitative Report, 14, 1, pp. 42-60.
• Dooley, L. M. (2002) Case study research and theory building, Advances in developing human resources, 4, 3, pp. 335-354.
• Eisenhardt, K., M and Graebner, M., E (2007) Theory building from cases: Opportunities and challenges, Academy of Management Journal, 50, 1, pp. 25-32.
• Eisenhardt, K. M. (1989) Building Theories From Case Study Research, Academy of Management. The Academy of Management Review, 14, 4, pp. 532-550.
• Tavallaei, M. and Abu Talib, M. (2010) A general perspective on role of theory in qualitative research, Journal of International Social Research, 3, 11, pp. 570-577.
• Wacker, J. G. (2008) A conceptual understanding of requirements for theory-building research: guidelines for scientific theory building, Journal of Supply Chain Management, 44, 3, pp. 5-15.

Inductive thematic analysis has been likened to GT.

Nice question. The answer depends on what you mean by 'theory'. If you think of theory as a set of interconnected statements that link conditions, the social mechansims they trigger, the conditions under which the mechanisms operate, and the effects these mechanisms produce (which I do), then it seems rather difficult to 'build' such a theory with any one project. You can of course 'develop' such a theory - i.e. advance an existing theory - by deriving questions from it and answer it using qualitative methods. Unfortunately, most of these middle-range theories are not in a state that supports their development. In my experience, you usually have to reconstruct the existing theory from bits and pieces in the published literature. Once you have done that, you have a framework in which you can ask a theoretical question that can be answered with qualitative empirical methods.

I recommend the book by Miles et al. although I am not entirely happy with their handling of social mechanisms:

Miles, M. B., A. M. Huberman and J. Saldaña (2014). Qualitative Data Analysis - A Methods Sourcebook. Thousand Oaks u.a., SAGE Publications.

Good question. Unfortunately, there's no straightforward (short) answer. That said, let me offer some quick thoughts. John Creswell (2013) articulates five types of qualitative inquiry, only one of which is grounded theory (GT). So be sure to investigate the other four types (case study, ethnography, narrative, phenomenology) for a more complete picture. Also, as Jochen says there are different types of theory; for example, variance theory and process theory. GT seems to me particularly well-suited to developing variance theory (because it builds a small set of well-defined variables/categories and situates them in a nomological network), but GT can also be used to build process theory (Langley 1999). Of course, Kathy Eisenhardt's (1989) highly cited work on building theory from multiple case study research and Henry Mintzberg's (2005) sage advice on building theoretical explanations from rich, story-laden data are well worth becoming familiar with, if you aren't already. Malvina Klag and Ann Langley (2013) pick up on Mintzberg's (2005) notion of "creative leaps" and develop it more fully in terms of "conceptual leaps" and the notion of abduction. (Pay particular attention to abductive reasoning, as similar yet distinct from inductive reasoning.) You also want to be aware of the so-called Gioia Methodology that is all the rage in top-tier, mostly mechanistic journals, which purports to "summarize a systematic approach to new concept development and grounded theory articulation" (Gioia, Corley & Hamilton, 2013). Finally, see Gehman, Glaser, Eisenhardt, Gioia, Langley and Corley (2018), which does a nice job of summarizing some of the approaches to theory building in qualitative organizational research mentioned above.

Creswell, J. W. 2013. Qualitative inquiry and research design: Choosing among five approaches. (3rd ed.). Sage.

Eisenhardt, K. M. 1989. Building theories from case study research. Academy of Management Review, 14(4): 532-550.

Langley, A. 1999. Strategies for theorizing in process data. Academy of Management Review, 24(4), 691-710.

Mintzberg, H. 2005. Developing theory about the development of theory. In K. G. Smith & M. A. Hitt (eds.), Great minds in management: The process of theory development (pp. 355–372). Oxford University Press.

Klag, M., & Langley, A. 2013. Approaching the conceptual leap in qualitative research. International Journal of Management Reviews, 15(2), 149-166.

Gioia, D. A., Corley, K G., & Hamilton, A. L. 2013. Seeking qualitative rigor in inductive research: Notes on the Gioia methodology. Organizational Research Methods, 16(1).

Gehman, J., Glaser, V. L., Eisenhardt, K. M., Gioia, D., Langley, A., & Corley, K. G. 2018. Finding theory-method fit: A comparison of three qualitative approaches to theory building. Journal of Management Inquiry, 27(3): 284-300.

I failed to mention above that in Ann Langley's 1999 AMR article, GT is but one strategy for making sense of process data. Others include narrative, quantification, alternative templates, visual mapping, temporal bracketing, and synthetic strategy. Note that narrative strategy connects with Creswell's narrative inquiry and that synthetic strategy is exemplified by Eisenhardt's general approach to theory building.

You might be interested to read about our experiences in combining Elite Interviews and Grounded Theory into one, the relevance and rigor of “constructivist-grounded theory in elite interviews” as a methodological approach. :

Tomaz Schara, Richard Common, (2016) "Leadership and elite interviews: Researching the challenges of EU rail integration in a Single European Rail Area", International Journal of Public Leadership, Vol. 12 Issue: 1, pp.32-51, https://doi.org/10.1108/IJPL-03-2016-0007