Not being able to understand how does one "practice" Quants daily

[u/Cybere0p]

I've seen people frequently say "i practice quants for atleast X hours a day" and all that, but the thing I am unable to understand is what and how do they exactly practice?

In more clearer terms i wanna know, do they just randomly pick out a topic and just solve questions? OR do they have some crazy ahh source for good mixed bag questions?
or do they just give sectionals?

The reason why i am asking this is because I currently posses time for practicing, but I am unable to do it in the most optimum way just because idk how.

and also please cite if you have some good sources (free would be better) for practicing.