"Professional" means that someone got paid to do the installation. It does not mean that they did it right. Usually "professionals" are paid by the job, so there is incentive to maximize revenue by taking as many jobs as time allows.
I am strictly an amature (I prefer "craftsman"). If I looked at the number of hours that it takes me to do anything on the boat (usually 3X what I planned), and what I would be willing to pay... Well, I couldn't afford me.
NONE of the visible crimps would pass my inspection. That red one is an el-cheapo butt splice. It looks like the others are too, but I cannot really see. EVERY splice that I use is heat shrink, and adhesive lined.
Depends a lot on the customer. When you have customers phoning 3-5 times a day to badger you, right down to Christmas day, and continually demanding the job be done faster and cheaper, while adding new things to the list...
We have a customer right now, who while demanding cheaper rates, and continually fighting over even a 5% over wholesale pricing on parts(to try and cover the cost of the time it took to find, purchase and get them) added an upgrade to every major system on the fly-bridge and wanted the whole thing in the same time, with no margin on the parts, and labor at cost.
The boat in question came from the factory with all untinned wire, and connectors that were the cheapest non-heatshrink type, without any labeling, on a generic wiring harness used in several models.
A lot of that factory wiring resulted in
WTF moments, and since the boat was written off due to an electrical fire that spread from the engine room and burnt a lot of the interior, and a lot of the wiring, it suggests that the standards exist for a reason. The customer bought it like that, and wanted a cheap refit to the highest standards done in no time at all, it wasn't a very fun job.
Most people prefer to do a better job(I like to believe), but if harrassed long enough, will get it done faster, and cheaper, while trying to at least keep as much quality as can be salvaged. Often it's still miles ahead of factory.