My only caveat is quality of the parts ? I did a DIY battery repair and part is so-so (can’t complain for £9), wife’s phone we did at a repair stand in “The Range” for £30 and which lasted a year before warranty replacement.
An iPhone 6 screen is about £15, so he’s doing quite well if he can do several per day. To be fair 15 mins is very quick so he must be pretty good, I did a 6s screen yesterday (a bit harder apparently due to all the glue) and it took me about 90 mins. The screens are not as good as Apple ones but they are OK especially if it’s just gonna get broken again 🙂 I’d recommend investing in a decent case though, cheaper than a repair!!