Hi @Eric Wang
I would say it just depends. I rehab my rentals to a certain degree, I know what to rehab and what is more time/cost-efficient to sub out. If you don't have the skill, it will be a steep learning curve, especially if it's a bigger renovation. It can be extremely beneficial, economically-speaking, and incredibly gratifying; however, you might want to look at the opportunity costs. What are you giving up in order to take on the project? Money? Time? Etc? Also, what are the up and downsides of doing the rehabs yourself...
Also, take @Brenda E. advice, it's good to get quality Contractors. I have guys I have worked with over many years, and I can count on them being there when I need them (they fit me in their tight schedule when I call). If you find a good Contractor, hold on to them tight b/c they are worth every penny. They get you out of tight situations.
Lastly, if you decide to take it on yourself, @Account Closed's advice is great too. You might want to act as a General for yourself and sub tasks out. The Quick response is (1) yes rehabbing is great, but with caveats and (2) it all just depends.