After practicing today I notice that I do sometimes pull the 1st slide. It's easier due to my confined practice area.

Emptying a slide while playing a solo in front of the band can be tricky. I don't solo in front of the band very often anymore but I remember Fred Dart suggesting to me, "...if you have enough time during the rest, turn to face the band while they're playing and dump the water – hoping not to hit your shoes".