First of all, I must say I've never had a problems with making cables by myself, last years stopped using cable testers just because they always say the cable I've made is ok.
But I see there's a lot of the factory-made cables on the market, they became cheap and in addition you may choose any color for the better management. Some people say the factory made cable is always better than you may do.
As there could be couple of the different situations, let's split a question:
buy or make a cables for the networking inside a rack?
buy or make for the networking outside i.e. to users' computers, to other racks etc.?
Personally I would always buy cables and always do buy cables in large volumes.
The reason for this is that unless you are making cables for home you are making cables for a business. It takes time to make cables and you are paying people/you are being paid by the organisation you are working for. Unless you are making them in very large quantities the amount you save from making cables yourself does not cover time cost of the time taken to make the cables.
Also as you said you can buy multiple colours and most lengths, failing that there are companies out there who will make you any length of cable you want cost effectively.
Hope this helps.
I can not make cables at a rate fast enough to compete with the prices from MonoPrice or Ziotek.
The only exception I make is for cables that are particular long, that have to pulled through conduit or holes without connectors on them, or when exact size matters. In that case, I do my best to borrow a appropriate cable testing hardware to test my work.
My preferred method is to keep a stock of premade cables on hand (in a couple standard lengths), but always have a spool of wire and a box of plugs as well so I can make longer or custom-sized cables on demand (or if I run out of the premade ones).
It just doesn't make sense to me to make cables. You save some money on the materials, but you quickly surpass any savings with labor.
You also probably aren't going to test and certify every cable that you make, meaning that it could turn into a hidden little problem in the future. I'm a big supporter of having quality cabling. After all, if layer 1 is unstable, the entire stack falls apart.
We buy all of ours. The cases when a selection of 6' and 15' cables can't fill a need are very, very few, and we'll crimp in those cases. I asked our Telecom people about this and their answer was:
This is greatly helped by the fact that we don't have to run drop cables from the network rack to the server racks, we have sub-floor jacks positioned next to the server racks. THOSE cables are cut to length, of course. Because of this 7' and 15' cables work for the vast majority of our equipment-wiring needs.
I don't know what they do out in end-user-land. They probably have a wider selection of pre-made.
I've been in both low-end and high-end "datacenters" recently. It all depends on how much time you have - and your budget.
In racks and patch bays, I would stress you use pre-made, and colored. We used one color for each of network devices, printers, servers, and then the blue for users and ip phones. Otherwise it will get messy in a hurry.
Everywhere else, it's up to you and your time. If you think your boss sees you as "idle" all the time, then crimp some cables in front of him/her and look busy... Your brain will turn to mush.
If you can I would spend your cycles learning more about the devices you are plugging in. That's what will pay your bills in the future. :)
Not sure I understand the logic of not testing a cable you're just made "because they always say the cable I've made is ok." To me, the small amount of time it takes to test, even multiplied by the number of cables I've made over the years, is well worth the time saved diagnosing a resulting problem caused by the rare event that you missed a pin or crossed a wire, or that the length of cable you've just put ends on has a flaw.
For cat5/6, I'll use cables I've made both in the rack or an end run, but I test them first.
When I was in my old job, I had this exact same question. We initially had our student assistants make all the cables we needed, but we realized that it took time and they hated it. Eventually, we started buying cables of standard length, but kept a spool and ends on hand for situations where we needed an exact length (or when the pre-made ran out). That ended up being a good solution because our students still got some experience working with cables, but they could spend more time focusing on doing real work.
In the past, I've used pre-made cables for "short" cable runs (in a single rack or between nearby racks), while making cables that go any longer distance in under-floor cable channels.
Main reason for that is that it's much easier to get the cable in place pulling it from a well-designed cable box (or from a cable drum on a drum roller cradle) and not having to care about the connectors until the cable is actually in place.
But, unless you're doing quite a lot of "data centre"-type cabling, I'd say using pre-made cables is a better option, since you'd have to be pretty good at doing cables to make the time spent crimping them be less than the difference between cable and connectors.
Edit: Another reason for making cables is that most pre-made cables are not made fire-retardant and that's usually a requirement for any cable placed inside a wall of floor cavity (like data centre raised flooring).
I prefer to buy my cables in different colours (depends on usage, for example in firewall or server) and always have the needed cable, connectors, tools, bridges for use when needed.