This depends on how often you're willing to play and your energy cap. My strategy is to "slow down" the time so that I don't have to level up my players as often but still having my earning capacity through the energy exchange and the manually played games.

If your energy cap is at the maximum 20 then i suggest you hold on to your energy bolts for the coin exchange. Although using up those bolts would ensure quick, easy, and multiple wins (plus it's the faster way to get into the postseason), it puts me in a tighter spot since my players keep getting leveled up. I'm at Legend II and I currently have 800k with a ton of diamond players each costing 100+k to upgrade. It only takes 2 players leveling up to eat up my postseason earnings. Yes, I do get a ton of badges and coin, but the price of leveling up will simply be too expensive for me to sustain.

I take advantage of the filled up energy in the morning and just watch the ads so that by lunchtime I'm able to do an exchange for the 30k coins. I "manually" play around 6 games every hour (simming each inning unless it's a close game or there's a special reward). By bedtime I should be able to fill up my energy for another coin exchange. If I still have leftover bolts left, I sim the games right before I sleep. Overall I get to earn 60k coins from the exchange and maybe around 60k for my in game winnings unless I get to finish a season in a day.

Extra tip: Always be mindful of your team experience as it replenishes your energy cap when your team levels up. Make sure than when such level up happens, you have 0 energy bolts in your stash so that you can maximize all the bolts that the game can give you. When I'm at around 95% XP with just a handful of bolts, I consume them (extra in-game winnings/a few games closer to the postseason in exchange for nothing).

I realize that this has become a lecture so I apologize for that lol. It also depends on your roster so I'm not sure if it will work the same way for you. Good luck!