I am a member of PokerStars for many years, and their rule for regular tables is that a player can only sit out for 3 rounds of big blinds. Blinds are not posted for them i.e., there is no “Away-post & fold”. After missing 3 big blinds, the player is automatically removed from the table and the seat is then open to other players. This works very well.
Thanks for sharing. But I think you’re referring to ring games only, we have a similar rule ourselves. For tournaments they take the same view as us:
http://www.pokerstars.com/poker/tournaments/sitting-out/
I’ve copied the text from this page below for your convenience:
Why “Sitting Out” isn’t against the rules
A player in a “ring” game (a non-tournament game) can click “leave table”, and take his chips out of the game at any time. They can do this because each hand is its own separate event. If a player sits out too long in a ring game, we do remove them in order to free up the seat for another player.
A tournament is not like a ring game, however. For their “buy-in”, they receive their starting stack of chips, which are not from their chip totals but are instead just scorekeepers for the tournament. Once the event begins, it must proceed until one person has won all the chips.
For the same reason that players cannot just choose to pick up their own chips and leave, we cannot arbitrarily remove the player and their chips from the event once it has begun. Every chip in a starting stack of a tournament must be at the final table in order for a game to be fair to every player.
It’s best to think of a player who is sitting out as simply folding every hand. This is a completely legal tactic, as it is up to any individual player to decide his own best strategy. There is no rule, for obvious reasons, against folding every hand.
Therefore, what these players are doing is not against any rule, and no action will be taken against them.
For the same reasons, we cannot make changes to the system to discourage this activity. Once a player has paid their entry, they are entitled to play (or not play) every hand that their chips will buy them.
A player who is sitting out actually puts his opponents at a significant advantage. The player who is sitting out is still forced to pay his blinds and antes, and is never able to build his stack. On occasion, a player in a one-table Sit & Go might blind off into 3rd place, or maybe even 2nd, but players who employ this strategy are usually far worse off than those who play their best game.
If players are actually reaching the payouts and winning chips by sitting out the entire time, this is a sign that the play in these events is far too loose, and you should adjust your play accordingly. You will find that this is often the case with all play money chip games. I’m sure you’ve noticed, for example, that players will go all-in holding virtually nothing when it is play money.
We hope this clearly explains why this is neither against the rules nor something we can possibly police. If you were to play in our real money cash Sit & Go events (available only on PokerStars, not on Pokerstars.net), we believe you would find that very few players are sitting out, and that the play is much more realistic with real cash on the line. One-table real money Sit & Go’s are available for as little as $1.10, and multi-table Sit & Go’s are available for as little as $0.02!
In addition, we have implemented a limit of three concurrent play money Sit & Go events per player. Players can no longer sign up for an unlimited number of events in an effort to accumulate chips without playing.