I think it depends on whether you are aiming for knowledge or speed/automatic-ness as well. Lots of problems in a row will get you speed, and then spaced repe

I think it depends on whether you are aiming for knowledge or speed/automatic-ness as well. Lots of problems in a row will get you speed, and then spaced repetition will help it stick long term. For really fundamental maths skills you don't want to need to actively remember it, just do it without thinking (so your thoughts can be devoted to the higher level problem you're working on).