Once my analysis provides me a team that is regularly winning series, I make sure to give it enough of a trial run to take deeper runs into the tournaments. Understand that in a 32-team tournament, 75% of the players are likely putting in as much time if not more. From there, it can be a bit of a crapshoot, but if you can keep entering with a team that's being competitive, you can keep running it out there without much effort. If I can collect 5-10 packs a day on a team that requires little maintenance aside from entering, I feel pretty good about that.
It's a bit of a personal cost/reward game... what are your expectations and can they be achieved if this is a realistic payoff? I expect to lose the majority that I join and end up having surges on days when I'm ready to give up my strategy.
Free-to-play, with an emphasis on the play.