In my case I flew on 25 days over 4 months (Apr-Jul), I found that early on more than 2 hours a day was counter productive (brain dead) especially when there was a problem. Later on 3 or perhaps 4 hours was OK but frequent breaks are needed.
Don't gauge to much on the first few hours, some people start slowly and speed up, others (like me) start quickly then hit a mental or physical block and slow down before getting the hang of something.
Doing it reasonably quickly will definitely save money and frustration having to relearn things.