The time off= time on theory is just SO oversimplified.
The time you take off should depend on the type of gear used and not the length of time you were on it for.
Ie if you were to do a 4 week sust cycle then then take a 4 week break, there isn't actually an 'off' period due to its long acting nature.
On the other hand, if you were to do a 4 week prop cycle, then a 4 week 'off' period would be more than sufficient.