you guys are right of course, i'll continue this way thanks!
another question: when you go on gacha, there are more probabilities to find good stuff with the group of 10 or nothing change if you take only one per time?
The only benefit to rolling 10 at once versus singles is that there will be at least one SR or higher guaranteed. This means that if you have 3000 jewels, might as well do the 10 roll rather than 10 singles since you may get unlucky and get 10 Rs.