All potential bonuses

No, you could find any glove with 3% str on them and pass 4-5 60%s on them.

Can't really speak for other people in general, but if I switched to an 8 atk (4 60%) glove, it would need to add 4% or more str to be an improvement over the 15 atk SCG I currently use.

And just getting that 4 60% is only a 26% success rate, meaning probably buying 4 gloves with over 4% str, and about 15 60% gfa.