Why is there such a range of gas / oil mixtures recommended for 2 strokes?

I recently bought a saw that recommends 25:1 gas /oil ratio, I have a trimmer that needs 35:1 and a small generator that requires only 50:1, just like the small outboard I have for the dinghy.

How come different manufacturers recommend such a wide range of fuel / oil ratios? I suppose some of the engines run at much higher revs than others, like the saw and the trimmer. the generator chugs along at 3200, and the outboard might hit 4000 revs / minute while the saw and the trimmer spend a lot of time working at around 8000. But some saws recommend 50:1 ratio.

Any answers here??

Thanks