I've had periods where I've paid for tokens, then for a while not paid and let my team(s) coast. The good and bad results have broadly been the same.

At the moment I have one team at Level 25 on which I concentrate on buying a monthly pass and occasionally an 80T pack, and try to keep it to about 90% at start of season to about 110% at the end. It's won lots of League Championships and had occasional CL and Cup wins. I have two teams, at Levels 7 and 5, who subsist on tokens from the daily award, and any won in competitions and Associations. They don't win League Championships as often and still pick up the occasional CL/SL and Cup win, but are still competitive at their Quality levels.

The game doesn't care whether you pay or not, it's just programmed to screw you over however you play...