I didn't like having to use it, because I didn't want to disrupt the group around me. There should be a way of binning burritos without actually using them...
You can, but only on the Companion app.
I've only ever used a burrito successfully once. On a Crit City green cone of shame race, I was in second with a lap to go, a few seconds lead on a pack of 3-4 riders and about 10 secs behind the guy who'd jumped off the front a few laps before me. He then got green coned and I started chasing him down - as I came up to pass him, I didn't want him to sit on my wheel, so I hit the burrito PU just as I was about to overtake and despite his surge, he wasn't able to keep up with me. Ended up winning by just under a second from the chase group.