Sometimes I can knock one off in 15 minutes, and sometimes it takes hours and hours and hours to figure things out. The difficulty range of these challenges is quite wide, so as long as you can get through them don’t worry about how long it can take.
Whatever it takes you solve it! Just, never give up, check references, ask for help in the chat rooms, do diagrams and be serious about solving it. The thing with FCC is that the pace you take is off to you. I solve mine in 5 min to 1 hr. The hardest ones that involve recursion or hard stuff like advanced math could take me the whole day (with breaks) or little 2 hrs sessions for a week.
I used to knock off 4-5 algorithms in 2-3 hours when i used to do intermediate algorithms, but as soon as i reached advanced level ,sometimes it would take me more than a day just because a single test failed most of the times. But i never gave up. It boosted my problem solving skills a lot. I also solve a lot of algorithms on codewars to improve further, and it is quite fun to be honest.You should try it out too. There’s a clan for freecodecamp as well, there are a lot of campers who are quite active on codewars.