That is a god awful way to splice data and should NOT be standard practice.
If you have to splice individual pairs or a line together only something like this should be used for a good lasting connection. https://www.amazon.com/DGZZI-Waterproof-Gel-Filled-Telephone-Connectors/dp/B07Q1L8GDT/ref=sr_1_10?keywords=network+cable+splice&qid=1569936490&s=gateway&sr=8-10
I have used these isolations many times. I have made this electrical connection many times and they have never failed. Nobody claims that this is the standard for Eth on a daily basis but in an emergency situation when a new cable cannot be laid, OP can use such a connection.
However, if you are referring to photos with electrical insulating tape, they are not mine and they are not advice but an illustration which is to give visualizations of wire-to-wire connection for OP. Familiarize yourself with the topic and context of the conversation.
What you provided in the link is “god awful” in my opinion. I also dealt with it. I would not recommend it especially the cheapest ones. Many times they lost contact and had to be replaced. But since you like them …
I worked in telecom for a few years and the ones I linked can carry a signal with over 50+ splices for a mile with no loss. If you look at the post I replied to it was very clearly the one with electrical tape.
I worked for ISP for quite a few years. We put networks based on cat on a daily basis in various places. All buildings. Air connections as well as between buildings.
Maybe you had good luck with them. I had to replace them more than once. 50+ for a 100/250Mhz signal?
Personally, I prefer soldered connections. From experience, my statistics simply speak for such a combination. I don’t trust anything that clenches. Too much risk that problems arise. But it’s a matter of individual approach and preferences.
But we depart from the case … OP does not make uplink between the USA and EU just wants to put rj45 on a thin cable. 
As for quoting, for some reason a whole tree of posts appeared to me. So it was hard to guess which post is cited. But rather it should be obvious that such a twisted wire and tape is not a good solution and it is only a visualization for something else. 
And there are several effective ways to connect wire … Many roads lead to Rome.
Soldered can be better, but for most people simple beanies are more than good enough. And I have had to replace tons of them as well and never due to a faulty one, just user error. Pairs not all the way in, not compressed all the way. Shit like that.
These are always an option.
Obviously, if you work in telco and need to do a bunch, that’s not economical, but if it’s just one or a few…
The user … One of the reasons why I prefer solder connections and those that also have stress relief points.
I have dealt with a mass of situations. Dogs, Cats, Children, Drunken idiots … There is a saying “idiot resistant solution”. Very often, this average user is the cause of the problem that I need to solve / repair after him. For this I prefer to use an armored solution than to do something twice.
Yes, this is also a solution but not for OP rather.
Oh right, flat cable… my bad… In that case, I change my alternative suggestion to terminating it in a surface mount box.
It is also a good solution.
It is time for OP to choose the solution that best suits him.
solder and heat shrink tubing.
