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Should be 9 Months, and Idle Master

Before summer sale. Heck, probably before summer sale's date was leaked.
The restriction stays for a few weeks after a refund/game removal. Also, keep in mind that when a publisher uploads a new game on Steam, they can set what time the cards will drop at manually. Normally it was after 15 minutes and 1 card per every 15 minutes afterwards, but it can be set to large intervals and a larger starting time. (I had games before the refund option was even a thing where the first drop happened at hour 3.)

If you put it on idle each game then upto 2 hours simultaneously, then wait on one game, click next, then wait on the next. It should give a card for each game with a few exceptions. It appears that a few games don't like the glitch as much as others and it may take some fiddling with before they start to drop. On the main though I get a card for near enough every game.

It also helped closing and re-opening steam, just fiddle with it, find something that works for you. But the main thing is, changing the game you are playing makes steam drop a card for the game. It could just take some time for it to work. Wait 5-10 seconds on each game before clicking next. Hope it helps! :)

No. I must return cards to the person who hired me to idle ASAP. Being restricted is very very time consuming, considering i'm "professional idler" I have no time to waste. If i knew what are the consequences I would never refund that crappy game that draw me into this