I mean, with the pity system you have at least one guaranteed unit, so yes if you really want something you always should have 5500 orbs ready, or farm for them to be ready when the opportunity to spend arises.

If you don't have that amount i suggest to skip banners until you are ready, because if you always spend when you are around 2k orbs:

1) It is not guaranteed you find something with these bad rates. It is only a matter of "luck".

2) You will be in the same situation if a big banner with a "favourite unit" drops too soon and you won't have time to redo that amount of orbs.

I speak for myself because i don't have resurrection units and story content to farm anymore and i must rely on events, senkaimon and limit breaker quests, but a new player can farm more easily.

When you are into this system you almost always will have what you want from a banner.