I typed all this out last night and forgot to hit send. Now I feel late to my own party.
I'm not sure I could do it in 30 seconds anymore, considering I've gone from doing literally 1000+ of them in a year in the early 2000s to doing... half a dozen, tops, when I need to repair a patch cable.
In my prime, though, yes, 30 seconds was about it. Mostly it was practice. I did a lot of very large cabling projects of all sorts back then, so it was hard not to get good at terminating. I was also "The Termination Guy" (not the Terminator, that's trademarked and also a dad joke) so I crimped or punched down a majority of cables for a few years. And did quite a few phone systems when cross connecting various things required making your own cables unless you wanted it to look like trash.
The way I did them was this:
- Strip the jacket and cut off the string. I strip about 1.5", at most.
- This part is the first trick: Move your pairs so they fall where you want them. I pulled the orange to the left, green next, blue, then brown. I just roughly put them in that order so when I untwisted and flattened they'd sit better.
- Untwist your pairs almost all the way back to the jacket.
- Put them in order (WO, O, WG, B, WB, G, WBr, Br). They may not quite stay there but we'll have a chance to correct in a few seconds.
- This part is the second trick: flatten the pairs on a smooth surface, like the round shaft of a screwdriver or on a flat tabletop. I do this by pulling them between my thumb and the surface. This is to get the conductors as straight as possible so they stay in order when you cut them and put them in the connector. Do not apply too much pressure or you can strip jacket off and that's bad.
- Cut them flush about 3/4" from the jacket. I don't use the feed through RJ45s; I prefer the ones that wires butt into.
- Shove them in the connector and check colors. Push the jacket up into the connector as well. If you don't, you'll eventually have jacket popping out from the stress.
- Crimp. I have the same non-ratcheting crimper that I've had since I was 17 and I still prefer it. I have never had problems with it not applying enough pressure and connectors always seem to get stuck in ratcheting ones.
- Test it. Always test it.
I can try and take video of this at some point.
I really don't like the feed through mod plugs. Even at their best they require more prep and are slower to get wires into then others. And I find that even with the actual tool to flush cut them, half the time wires are still left hanging off the other end. That being said, for those who don't do large quantities, they are guaranteed to have fewer mistakes since you can more easily check your colors.