Can I run multiple games at the same time for card drops?

[Ohforf]

I have a few games with really annoying card drop rates. For example: I run one of the banned Zatwor games over night in windowed mode and didn't get a single drop. 18 hours in and only 3/6 cards.

Can I run all those game at the same time to farm cards more efficiently or will Steam just ignore all the games except one?

[Eldin]

You can run up to 32 games at the same time, but drop rate will lower itself, so it's not efficient to do that.

It's best to use app that'll automatically idle all games for you.

I use Idle Daddy from Google Play store.
It's running on phone in background so you can idle games 24/7 and it doesn't use much battery.