I fit bathrooms for a living which makes me a 'multi-trader'.....you can be 'more than' competent at multiple things you know!
Lakey, everyone has their strengths and weaknesses. I believe in being the master in 1 trade. I can do plumbing, joinery and electrical work ( obviously I get my electrician out to check and sign off ANY electrical work I carry out). This all started at the recession as I wasn't working and all my best mates were. They are joiners, sparkys, plumbers and plasterers. I don't touch gas works, not gas registered. But typically speaking I would rather lose money and save face than try and do another trade on a customers house.
I am not trying to say tradesman can't be multi skilled but typically plumbers are good at plumbing, tilers are good at tiling, plasterers are good at plasterering, so on and so forth. My dad is a builder he is multi skilled. Great at tiling, plastering, electrics (NICEIC registered) and plumbing but he is absolutely pish ***** at joinery work. So much so, he never touches joinery work.
The point I am making is everyone has an Achilles heel, something they aren't good at. In my opinion no one can truly be top notch in every aspect of building work.
I also do bathroom renewals. I always get other trades in. Always! Typically I carry a joiner, plumber (gas safe registered), plaster, electrician (NICEIC registered) and a Tiler (myself or one of my guys). In my opinion it is much better to spread yourself over 3 to 4 jobs as appose to 5-6 guys tripping over each other on the 1 job.