[Royal Hawaiian Opihi]

Here's what the rules say:

Also, players demoted back to the Taxi Squad receive a bonus to their current year salary based on the number of consecutive weeks on the active roster immediately prior to their demotion at a rate of 25 cb per week active. For the purposes of this rule, a week will be defined as passed once an NFL game has been played, However, once a player is moved to the active roster They'll earn one week's bonus whether or not they get deactivated before the upcoming Sunday game.

So using your Pierce example, it's not the number of GAMES he plays, but the number of NFL WEEKS he's active. This past Tuesday began his 3rd NFL week.