There's no limitation on the number of measures one can generate or adapt for a given study. However, for each new or modified measure, there's the obligation of trying to collect sufficient data to make a case for its technical quality (e.g., evidence for reliability, validity for the intended use of scores).
Dear @Amani, although there's no limitationon number to the number of surveys and interviews in a single Ph.D. study, the time and money costs of such repeat efforts could at times be prohibitive for the student.
There are standard procedures for research result validation.