If you intend to play slots for fun, you can try as many titles as possible at the same time.
Of course, no one wants to carry a calculator and a notepad to decide if they should continue playing a title or not. And, a player will not want to move to another here and there after a spin.
If a slot gives you unexpected results, you ignore it. If the outcomes satisfy you, keep playing it but also try other titles to see if there might be a better one. In this way, you will progressively narrow down your selection to slot machines that tend to give good results.