Can anyone predict when the bonus will land?
Choosing how many spins to play starts with one fact: the bonus round does not come on a schedule. How often it arrives is not known in advance, and the result of one session is random whatever the RTP. A high RTP does not mean the bonus lands sooner, and a short run of spins tells you little about the next one.
Deciding between RTP versions starts in the game rules, where Royals Casino shows which version is running. The reels themselves do not reveal it, so check the rules before you set a stake, and treat the percentage as a long-run figure, not a promise for your next session.
Planning around the biggest prize means accepting that it is a ceiling, not a target. The maximum win of Razor Returns is x100,000 the bet, and that ceiling is reached very rarely. Treat the figure as the outer edge of the game, not as the expected result of any spin.