Everyone is going to be different with this.. and really the main thing is how much do you care about your health.
When you blast and cruise, or go on TRT after a cycle, the general "time on/time off" rule doesn't apply as much. Many people will blast for 16-20 weeks, come off for 8 weeks, and then blast again. It is not uncommon for people to only come off for 4 weeks like you stated.
If you choose to go this route, you need to make sure to be getting blood work done regularly. Steroids are notorious for destroying our lipids and cholesterol. So, while you may be living a very healthy lifestyle, with a good diet and workout regimen.. your blood work might show you as being the equivalent of a 350 pound man that eats fast food 5 times a day. It's a good way to die suddenly from a stroke or heart attack at a young age.
The longer you stay on, the more likely you are going to be to develop other issues, like and enlarged heart or prostate.
There's also the fact that your body does need a break from the oversaturation of the androgen receptors.
Just take a minimum of 8 weeks off.