It depends on your cruising mode, employment and skill level. As a full time live aboard cruiser you should know your boat inside out. The best way to do that is to DIY. As a well paid weekend warrior, let the yard do it.

I have observed the opposite, the in the past well paid retired cruiser that does not bother to know his boat. That is the guy that gets into trouble. I have known this type of cruiser. He had the same fix it list port after port. Some supposed professional put a band aid on something and it lasts long enough to collect his pay. Next port - same issues all over again.

I have done almost everything there is to do on a sailboat and it has been a learning process. There are jobs that I re-did because I didn't like the way they came out or a few years later I thought up a better way to do it. I gladly pay the welders and machinists that have skills and tools that I don't have. The rest I do myself. If you take the time to think the job through in advance your success rate goes way up. I did an engine swap in less than a week, only paying for the crane. But I spent twice that time preparing for the job.

I too am getting older and have paid to get the bottom sanded, the hull waxed, etc. but I would not pay yard rates for that work. I found the independents that don't have the huge yard markup.

Remember, when you are in a storm wondering if it will all hold together the professional is in the pub throwing back a few. Who cares more about how well the job was done?