Have you done much cabling work?

Experienced installers (well, the good ones) have a range of tricks and methods they use to speed up the process and limit their exposure to risk.

Risks might include ...
damaging existing equipment, structure, wiring, whatever.
Damaging furniture (moving it, working over it)
Drop ceiling hazards (old Flourescent lamps falling out, panels falling down because you looked at them sideways)

Cable failures; installed cables may not meet certification specs, unexpected lost packets, slow speeds, intermittent issues.

Basically, your ‘costs’ include a lot more than the cost of the cable and cable terminations.

I can post later about cabling tricks of the trade