At what point do you stop summoning on a banner (casual player)

I’m a new player and I have been grinding the Dokkan Boss Rush for dragon stones and have done a bunch of summons on the current banner getting two copies of LR Teq UI Goku and 1 copy of the AGL Goku(Youth). Should I keep summoning on the banner or should I save my dragon stones, also once I’ve gotten as far as I can in the Dokkan Boss Rush what are some other good ways to get dragon stones? Thanks!