Thoughts on 1 LI for combat?

I have been thinking about this for a while now, and still haven’t figured out the most optimal way to play this game, nor if it is feasible.

I’m a Sylus main, I like the other LIs too, but honestly, I don’t really care that much about them and would rather invest all my resources to try to get all of Sylus’ memories with maybe the occasional Zayne or Caleb card.

My main concern with only having one main LI though, is not being able to clear more "endgame" content. Currently, I have 2 more or less okay built Sylus teams, but cannot achieve more than 18 stars in SHC, or clear 100 in the open orbit. I am obviously using crit teams as I don’t have the right stellactrums since Sylus’ main colors are green and pink. However, I feel like I’ve reached a point where brute force doesn’t really work anymore and I doubt it will become any easier with time. So I am a bit conflicted about only getting Sylus cards if this means that I’ll be missing out on ways to farm diamonds or straight up not being able to progress.

So my questions to low spenders/those who main 1 LI is: How do you guys pull on banners and manage your ressources? Do you think having 1 LI is viable in combat, will it become worse or better with time?

EDIT: I forgot to mention that I was a low spender (Aurum/Yearly pass with the occasional splurge if I really want a card).