Unfair
Can you shuffle all theme packs together at setup instead of sorting them by theme?
Not as a permanent habit. The designer does not recommend a standing combination with more theme packs than players, because the extra cards slow the turnover of the Park deck and make blueprints harder. A larger combination such as six packs only makes sense if you always play with 5 players. To keep setup quick, give each player one theme pack to split by card type, then have players each shuffle one card type; reverse the process at pack-up.