Plan a session around fun, not results
Deciding whether to hold out for the feature round means accepting that nobody can say when it arrives. The timing is not known in advance, and the result of one session is random whatever the RTP. A quiet run of spins does not mean the next one is due, and a fast trigger does not mean the game is hot.
Open the game rules before you commit a stake, because only they state which RTP version this lobby runs. The rules are the single place to settle that question, so check them each time you return to the game.
Treat the top prize of Jammin' Jars as a ceiling, not a target you can aim for. Reaching it is uncommon, and no amount of play, time or stake brings it closer. Plan your budget around how long you want to play, not around that number.