Random results and bonus timing
Choosing a stake means accepting that how often the bonus round comes is not known in advance. Each spin is random, so the result of one session is random whatever the RTP. An RTP figure describes the average return over a very large number of spins, not what happens in your next hour.
Before you stake, open the game rules and read which RTP version Casino Rocket runs for this slot. Only the rules show that version, so check them before the first spin rather than relying on any other page.
Chasing the top prize on Big Bass Splash means accepting that the maximum win is a ceiling reached very rarely. Plan each session around your budget, not around that ceiling, because the top prize cannot be promised to any player.