Free spins timing and single-session results
96.71% is the RTP of Big Bass Bonanza, a long-run average over a very large number of spins. It says nothing about how often the free spins round comes, and no one can know that in advance. The result of one session is random, so two players with the same bet can finish with very different balances. Nothing in the RTP shows where one session will land.
96.71% RTP is listed on this page, but which version is live here is shown only in the game rules. Versions of the same series can carry different percentages, so read the rules before you play. The version named there is the one that applies to your session.
A$250 is the highest bet allowed on this game. The maximum win of Big Bass Bonanza is a ceiling reached very rarely, not a target for any session. Reaching it depends on luck, and a higher bet only raises the money involved.