Everyone is different and have different skills.
It would then only be reasonable to expect a very wide range in answers depending on skills with additional impact of factors such as money and time AND interest...
I like to do as much as I can with the time I have which is often very limited.... I actually do some very late night work on my rehabs... because I enjoy it and can get fast gratification on work performed. I recently tiled kitchen cabinets and a half wall.... just because I wanted to give it a try. Tools didn't cost much, a wet saw about $75.00 and the materials less than $200.00 total. I estimate it increased the value by $2000.00 and really looked good. I would have had to reface and re-top or replace the cabinets. I liked that so I did the Shower in a bath. Easy work and looked great and the bath just took one evening to do.
For jobs too large for me or those I don't want to do... I hire handymen that I also often use in the Property Management aspects of my Brokerage. These are normally available at less than "Union" price if you give them the ability to do the work as a fill in for their normal work. What type I hire depends on what job is to be performed... I don't want an electrical doing plumbing or an AC guy doing flooring, or a roofer doing painting... simple get those that have the skill sets needed. An owner can make most "repairs" to a property. If your doing this for a Client... you would be better off using contractors and passing that cost on to them.... I personally try to reduce unneeded expense on my own properties... it detracts from my pocket money.
So the complete answer to your question is:
It Depends.
As far as properties, How much work cosmetic or major... really has no factor in decisions. It all depends on what the numbers are... with big repairs you factor in big cost and if the numbers don't fit your investment criteria move on to the next opportunity.