How often will the bonus round actually come?
Choosing Double Chance over the standard bet means staking 1.25x more per spin for extra Scatter symbols on special reels. Whether the bonus round arrives on the next spin, much later, or not at all is not known in advance. Every spin is random, so the outcome of one session stays open however the odds are set.
Deciding which RTP version to play starts with the game rules, because the version running in a given game is shown only there. Both versions sit close together, so the gap between them is small compared with the randomness of any single session. Check the rules before the first spin, not after.
Chasing the top prize means aiming for x15,000 the bet, a ceiling in Gates of Olympus 1000 that players reach very rarely. Reaching it depends on the bonus features lining up, and no session can be planned around that. Treat the maximum win as a limit on the payout, not a target.