What are the factors we should keep in mind while submitting the article to journal? Why many papers get rejected even though they contain proper content? Why few journals take years of time for article handling (Acceptance/rejection)?
There are multiple factors, the impact factor of the journal, the type of review, the stipulated response time, and if the content is still good, the volume of manuscripts sent may exceed the human review capacity and they may be selective and hence the high rejection rate
Concerning the reviewing time, sometimes, it is difficult for a journal to find reviewers for an article with a more specific topic. It seems the more interdisciplinary your paper is, the more time will be invested in its reviewing. Waiting for more than half a year is not an exception in such a case.