Accept the randomness and bet within your means
Before you decide how much time to give one session, know that the Free Spins round arrives at no fixed pace. Nobody can tell in advance how often it comes, and the result of one session is random whatever the RTP. Two sessions on the same version can end far apart, so read each run as one draw.
Before you rely on any RTP figure, open the game rules. They are the only place that shows which RTP version U2win Casino runs for this game, and the two versions differ only slightly. Check the rules once, then keep that version in mind for the whole session.
Before you pick a bet, read the maximum win as a ceiling, not an expected result. It is reached very rarely, and the money amount it produces grows with the bet size, as the figures table shows. Plan your budget around what you can lose, not around that top figure.