For in-rack patching, I'd always go with buying cables off the shelf as it is cheaper and easier to buy them in. I'm a trained network engineer and my time is relatively expensive - I could be doing higher-value work such as configuring routers and switches. Another benefit of buying pre-made cables is that the quality of moulded-on strain-relief is better than anything that I can make myself, and if I buy them with anti-snag clips, it makes decommissioning so much easier, too. Have you ever timed yourself making and testing a cable and factored in your hourly-wage to figure out how much it really cost?
I am work in an environment with several thousand servers, and where we can afford to keep an inventory of various lengths in 6 colours. I can understand that if you don't have budget or storage space, then it would be useful to be able to make your own for an urgent job, but the few times I have made my own, they have been appalling quality. When I've bought in cables, I've rarely had any quality issues (only 2 duff new cables out of thousands I've used).
For infrastructure cabling (under floors, through ceilings) I would always get a cabling contractor to come in and manufacture a solution to length - these guys are crimping and punching down all day and will do a far better quality job. I can also ask them to do things like clearly label each end of the cabling, that I would never bother to do myself.