Knowing where this game's answers end
Deciding how long to stay on a spin session depends on something no page can tell you: how often the Respin Bonus arrives. That frequency is not known in advance. The result of one session is random, and it stays random whatever the RTP. Two players with the same bet can finish with very different balances, even when both play the same number of spins.
Checking the RTP begins in the game rules, because that is where the running version is named. Only the rules say which RTP version is live, so read them before setting a bet. Summaries and reviews, this one included, cannot replace the wording of the rules themselves.
Deciding how much a session might return begins with the ceiling. The maximum win of Sleeping Dragon Ultra Dark is x20,000 the bet, and it is a ceiling reached very rarely. Read it as the upper edge of what the game can pay, not as a target that a session approaches.