Well, depends on how many 5* ninjas you have and how much you do elite instances, not including what you may pull from treasures with free draws and even draw 10s. And it depends on the ninja fragment as well since each have a different value.

You should into the collection of guides the mods made, which is helpful for beginners: https://forum-narutoen.oasgames.com/page/show-post-30175-1.html

Look under "Fragment Refine" - it will tell you which 5* ninjas from elite should easy to farm points

This guide helps, i didn't see a note on main frags, but I can check. With my current math excluding main frags it will be like every 3 weeks as I am doing materials on weekends. so for 100 frags - 30 weeks. and one mouse cause this one will brake.