There is no set number on how many matchups or picks can be offered in any given day. The number of matchups and picks is solely up to the Game Administrator (aka The StreakMaster). Most gameday boards are set by midnight ET, but the Game Administrator can add matchups up to four hours before the start of the event. (Ex. WGC Match Play Quarterfinal pairing in the morning, and then the Semifinals are later in the afternoon. The Semifinals won't be set until the Quarterfinals are over in the morning, so adding it when the pairings are known will be only a few hours before the Semifinals begin).
The Game Administrator reserves the right to add any matchup they wish.