Specializing lets you perfect the tooling and setup for a job, makes things go faster, you don't need to reinvent the wheel everytime.
I did forge and fabrication work, gates, railings, store fixtures, lighting, sinks, fabricating parts for waterparks and even parts for cars and trucks. It kept the work coming in and paid the bills, but every quote i was doing or project I got I spent a lot of time just figuring out how I was going to do it, vs getting it done and making money. Created a lot of unpaid hours in a day. Some jobs I made good money other days I was paying the customer.
I like the challenge of a new thing, but it gets tiring at times when you need to pay the bills.