It's one of the very few ways you can obtain fragments without using seals, another way would be Survival Trial but that's just random and you don't necessarily get the fragments of the character you wanted.

I'd suggest keep sweeping, it's random but sometimes you get 5 fragments in 3 sweeps believe it or not, and other times you get just 1. Don't sweat it and keep trying so you can get all your favorite characters upgraded :P

I don't know if this helps any but, I only sweep when I need certain fragments to improve character upgrades. Sweeping for EXP is not one of the greatest idea's because you only get like 1200 or something like that, if you want experience, I recommend bounty, and daily missions.

It is worthy to sweep because takes less time to do it and you get same amount of drops, it was said above my post too.

keep sweeping it helped me get 3 star ninjas in 2 weeks :)

Spamming ninja fragments every day is why you're not getting much for your stamina. The more you farm, the less they drop.

To reset them back to high drop rates you have to stop farming them.

What players used to do was farm ninjas for a few days then switch and farm gear. Then when they went back to farming ninjas the drop rates were better. This is the more efficient way to spend stamina, by spreading it around instead of focusing on a single thing.

Good advice, this seems to be the case. For ninjas I've been farming drop rate has been low. Went back and farmed someone I hadn't farmed in a while, and what do you know? Good drops.

Just focus to your primary ninja. If u still have more stamina upgrade equip is better.

you only use elites for ninja whose frags are easy to get.. for example... Hinata and Shikamaru