Well, I like to err on the side of caution, even if the side of caution happens to be somewhat irrational.
Yeah, but the issue is the longer you take laying them, the more likely the engineer will notice, and either flee or start shooting them. If the engy is preoccupied I can usually get 2 at their feet before they notice. They usually realise they're there right as the third one lands, by which time it's too late
See stickies on sentry = walk away or charge the demo and if you just put 5 stickies out on my sentry you are a candidate for a shotgunning to the face
No-one who knows how to play demo will be foolish enough to use 5 stickies on an un-wrangled sentry.
A veteran will go pop-pop-pop-boom.
A pro player... if any of you every play in Australia, and run up against a demo named "Hisnameisrobertpaulsen" (sometimes just paulsen, image is a blank red square), you will see what that class can do (and you should probably stack). That guy is insane, I've seen him do crap like a double sticky jump, and while flying through the air, shoot off two stickies at a sentry. Because of his velocity, they land at the same time, he fires off a third, and blows a nest about 1 second after the first one landed. Then he switched to pipes, and cleared the rest of the enemy team in 2 shots with a random crits. It was beautiful... shame he was the opposition
I sometimes play Engineer as long-range battery support, quickly deploy a lvl 2 sentry and use my wrangler to help assist my team's main assault wave, then pack up and move on once the area's clear. Takes a bit of work, but can be pretty useful.
I hate Wrangler's so much. Very powerful when used correctly :/