I played for a while without it, but found that a new golve helped add grip without the need to increase grip pressure.

That said, I'm sure that if I started washing my grips every couple of rounds, I wouldn't need a glove nearly as much.

That said, I just bought a pair of SMT gloves with a lifetime warranty - so I'll probably use a glove for the rest of my life. Any time the glove gets wet, dirty, whatever, for only the cost of shipping (both ways) I get a brand new premium glove.