Reasonable rest is good for the old guys, BUT if it's way too long, it will be rather detrimental. Past 32-33, your athletic ability goes down fast if inactive. It's also called rust, and it settles in rather quickly and it's harder to put away by a year once you're in the mid-thirties. Regaining great shape is not that easy. Also, at that age, being put away this long increases the risk you'll fall in love with the other aspects of life and don't crave the ATP madness as you used to being a young guy. The good thing is, time runs faster for you, thus the risk of letting yourself go, drinking and eating like a pig out of sheer boredom is probably not that high.
As a young gun, you need to play. You still learn, and what you try in training needs to be tested in the wild, refined if working, abandoned if futile. Continuity is the key. Ideally also, you want the peak of your tennis ability and finesse to coincide with your athletic peak. For guys who are 23 or 24, this hiatus is murderous, for it may mean they will never get as good as they could have no matter how hard they try. The good thing is, getting back in shape is much easier for you than the old dogs and wrecked ships. Times still draaags, thus you're at higher risk of boredom and overindulgence...