when there are free spins what you have to do is be very lucky to win, in fact I think that for slots you have to make micro bets and play for a long time, make many plays until you get the one that explodes and with considerable profits, in In the case of roulette, my main strategy had always been that of colors, but based on many losses, I think that betting on 0 and 00 is a winning strategy, I think it occurs more frequently.
In addition, in several articles they talk about it, and about the error that many players make, which consists in thinking that what is predicted will come out, which is called the player's fallacy.
That players fallacy is valid inside your post as well. You say that "making micro bets and hoping for a big return is the way to go for lost" but it doesn't matter. Because of house edge you could make a profit or you could lose no matter how you play, and in the long run you will always lose and that is what matters here. I am not saying that you should consider stop gambling just because of that, all I am saying is know that you are not going to have a win chance if you keep gambling for a long period of time, so you should gamble knowing that which would eventually mean that you will have a chance to have a lot of fun as well.
Slots and roulette if they have the same house edge means they would have the same chance for you to win/lose, because that is the only mathematical thing that you should be looking at when you are gambling, how big or small the house edge is.