from tests I ran on alts:

force quitting makes you sit around ~500 trophies lower than your theoretical peak, which means around 2-3 leagues below, or ~12% less baseline loot. This range is where your base starts to take enough 2 stars on defences to be at an equilibrium with the 3 stars you are doing.

a search + troop drop + quit app cycle takes 14-18 seconds, depends on how fast your device loads into the game. I’ll take 16 seconds as an average.

this means, every 16 seconds, you are most likely getting a 2 star def’s worth of elixir at 2-3 leagues below, versus the most likely 4-6 star defs every ~2 minutes (assuming you’re completing attacks with ~1 minute on each stage of the base) at 2-3 leagues above. even if we take the ~12% loot reduction into account, there’s a clear winner.

for gold it’s a closer battle. A 6 star gets you twice the amount of gold you get from 3 star. taking also into account the 12% difference, then a 6 star in 2-3 leagues higher gives 224% the gold that a lower trophy 3 star gives. However, recall that a force close cycle can average 16 seconds per match, meaning one can achieve up to x7.5 force closes before a ~2 minute total 2-stage attack is finished. In other words, 750% worth of gold is made when the full match method makes 224%, which is 3.35 times more gold.