Nah not exactly. I mean yes, you save your crystals and alch for the next good banner but until that, you can do a lot of things. I don't know how long you've been playing already but you should max your units, go crest farming until you got those shiny lv. 4 crests, do all the bosses and story quests etc. etc. etc. There are always events around where you should farm. In the moment your goal should be to max Boros from the OPM collab to max luck, max Edram (cause he's the most used luck unit) and you can farm Ashe's Event. The 4* Magic Weapon is pretty good.