Looks like the way I've been playing SM lately works out just fine for me. When I played daily, I sometimes got frustrated if I got into a bad streak of battles. Or when facing tough opponents which prevented me of doing the daily quest in a reasonable amount of time (for me).
But the way I'm playing now it's pretty awesome. I can enjoy the game, I avoid the beginning and end of the season when apparently everyone wants to level up, and I get to a reasonable high league for the amount of time played.
I also don't rush to see if I can upgrade any cards as I did before, as soon as I get some new cards. Or to buy what I need to upgrade. This is the first time I do that for quite some time. I had quite a few reward cards up for upgrade.
So far I love it. More like leisure playing, then a competitive one. And of course, I'm holding on to my cards. I haven't tried delegating some cards away. Maybe I should do that, but the thing is, I still love having my collection available to fight when I feel like joining the battle.
Here's an interesting screen from last season's rewards. 3 epics and 1 rare is pretty decent.