Should I increase my focus time past 25 mins or just keep blocking it out while taking 5 min breaks in between?

I should stay at 25 min, with 5 min breaks km between (and each 4 cycles a 15 min break), but this really depends on how you prefer to study. The danger of taking longer deep work sessions is that you get quite fast too much of it and often lose concentration.
Just do what feels the best for you.
Good luck with it, I know you can do it!
~ Arno D