I'm not bad at DIY and been doing it all my life, but sometimes I get something with instructions that don't make sense, so have to do it by trial and error.
BTW, in a previous life when I had a house in NZ I had a professionally made kitchen installed. The kitchen itself had some defects that I didn't pick up till too late ( so check everything before installed ) and the builders that the kitchen maker sent were cowboys. I had to redo everything they had done ( which was when I started doing things myself ). They couldn't even put up a wall that was vertical. I also had to sack the electrician they brought and get my own instead.
The <deleted> had the cheek to comeback later and ask if they could take photos. Luckily I wasn't there at the time, but my partner had to tell them that nothing they had done was still there.
Another time I had some alterations done, and the builder sent a "plasterer" to finish the wall board gaps, but he only did half the job ( very badly ) and never came back, so I learned to plaster myself.