No science behind this bro but I shoot for 3 months.
I blast 16 weeks on a bulk and 8-10 weeks on a cut so sorta in the middle of those.
I do get bloods though and want everything looking good before a blast for sure. Wouldn’t go into one out of range but I agree with cro that if your lifestyle factors are in check (no drinking, no recreational drugs etc), nutrition is good, supps/supports are appropriate you can avoid any severe issues on a blast.
for me it instinctively feels right to give the body at least half the year in a ‘normal’ status for basic health and longevity,