A tactic is a tactic and mostly requires on the spot visualization and calculation. You won't find the solution in the theory of R+B vs 2B because tactics are commonly the challenges that escape the theory. Fortunately or unfortunately depending on your viewpoint there are millions if not billions out-of-theory positions in chess. Occasionally there is a standard tactic for winning an endgame but most tactics are learned by endless training and putting your brain to work. Slowly it will start to recognize the patterns of certain combinations and your tactics sense improves.
In the world of "professional" problems solvers - there is a circus that travels the world in normal times - the best solvers will train every day by solving puzzles and studying them. Don't ever forget to study the solutions to puzzles you couldn't crack (you can do that in Puzzle Rush as well). All your training is to no avail when you ignore the feedback opportunity and just plow on puzzle after puzzle after puzzle.
A bit frustrated because I'm doing my first puzzle rush, and it looks like this ridiculous endgame is going to stop me just short of my goal of 40. Anybody know a good study resource for this position I looked for quite awhile in about all I could find was a comment from a reputable Authority that it's usually a draw. I'm not going to post the specific puzzle because I don't need anybody to tell me what's probably a pretty obvious answer to a Master Level player ( and anyway if I wanted to know that I just run it through an engine)... but if anybody could point me in the right direction with some tactical ideas, I'd be ever so grateful. I really don't have a clue, other than to make the one viable check I have with the Rook, or head in black kings General direction with my king since he's close to one of the corners. I don't see any obvious x-ray skewers Etc thanks in advance