I am currently in the fourth year of my Ph.D. and I am fully engrossed in my research work. Sometimes I find it hard to revise some forgotten concept from a related subject. What is the best strategy to revise old concepts while one is simultaneously doing one's research work?
For example in Physics, sometimes a term comes in the research work that I have somewhat forgotten but not completely erased from my memory. Do I need to do a thorough study of an old concept or just revise it in accordance with its use in the research work?