Unknowable Before the First Spin
Pace a session on the understanding that no one sets the timing of the bonus round in advance. Three SCATTER symbols may land on your first spin or on your two-hundredth, and the 96.50% return is an average measured over a vast number of spins, not a quota that pays you back inside one sitting.
Check the game rules panel before you stake anything, because that screen is the only place the return figure for this particular game is stated. Two lobbies can run the same title on different settings, so read the number on the screen you are actually spinning.
Treat the top prize as a ceiling rather than a target. The x15,000 figure needs an exceptional arrangement of symbols, and even the 15/15 Respin grid paying the extra 7000x bonus is an outcome most players never see in a session, however long they keep spinning.