From a practical standpoint.. back when I was a kid, living at mom's house, my room was out in the garage. I used to have to take about a 40m phone cable from my room, across the backyard, into the house, and into the phone jack there. It worked most of the time, but would fail if doors closed on the wire too hard, people would trip over it, it was very easy for someone to see it and just yank it.
I would imagine most secure facilities have doors that close automatically, unless prevented somehow, and each time that happens, it might have a good chance at just severing the cable, if not pinching it to similar effect. Ventilation systems would probably have inconvenient fans to navigate, or filter grates, or even scanners strategically placed to detect and neutralize drones just on principle of keeping competition down from fellow employees.
And then beyond all that. there's the time involved. Sure, if someone on the team is dragging it along, then it takes no more time than it takes the rest of the team, but logistically, trying to have a micro drone lug a bunch of cable behind it through the vent systems (which most cases probably won't take a direct path) to their target.. again, navigating any fans, filters, etc, might just take too long.
In my case above, the group was on a rather short window of opportunity, and they knew it. They had a specific time on a specific day in which to initiate the run, so coincide with a simultaneous run at a different facility. If you aren't familiar with the Silver Angel module from SR1, that was it. So, the likelihood of sneaking in first if the Johnson left was slim, unless they went in at a different time, which would have jeopardized the other Run, which would have made powerful enemies. It would have been fun to deal with, as a GM, had they gone that route.
