It's funny. I do computer service for a large organization with about 30,000 PCs across about 140 sites. There are currently six of us doing this work.
One guy carries into each site a laptop, a set of screwdrivers, a 400 CD holder packed with discs, a Fluke Nettool, an external hard disk drive, and a whole bunch of other ****.
I carry a Gerber 400 series multitool, a portable hard disk drive, and a tech single DVD with all of the software I need. I have some other tools and software but I almost never need them. Occasionally a network testing tool, but it's usually pretty obvious when a drop is inactive, and another group handles network infrastructure anyway.
Today I serviced about 25 computers, and I serviced about that many yesterday and again Friday. I've been doing it a long time and I know what I don't need to carry that'll slow me down.