Special Teams- So instead of needing to sign random players to long snap or punt for two weeks, coaches could strategically use their emergency replacements for a quarter here or a quarter there as needed. Without going through any statistics for this post, I'm going to go out on a pretty strong limb and say that I don't think there are any specialty players who play every quarter during the season anyhow. For some teams keeping their special teams guys out of 8 quarters will just happen naturally, while for others there might be some strategy needed to pull off all 8.
If a team breaks the rule and is heading to the playoffs, the players who played extra quarters in the regular season will not be eligible for double the amount of quarters in the postseason. The penalty will be served immediately. In other words, if your quarterback played 65 quarters by mistake, he's 1 over the limit. In your team's first playoff game he will miss the first 2 quarters of the game.
Players who play beyond the allotted 64 quarters will be compensated at double their game rate for each additional quarter played. So, if a player actually played a full 18 games (72 quarters) he would be compensated for an additional 8 games played at double his salary. With an expected 16 game season, that player would essentially double his salary by playing 2 extra games.
Since going over the cap is likely to happen with this bonus feature and we don't want the players losing out on money, teams who go over the cap due to the penalty will pay with draft picks.