No.
Not in my opinion.
There will be agreement, and disagreement on this.
But I firmly believe this to be true.
Individual response, and reaction (for what we are talking about), is just too Widely varying to attach a number.
If you want to say ... Those over 40 should be even more careful, and be even more prepared (I think as Hyde was saying), I could agree with that.
But I've also seen a Crazy number of guys who've smashed their natural hormonal production in their 30s. .... And even 20s.
I think a better approach (as I think, again, that Hyde was referring to), would be....
Nobody of any age should Ever mess with their hormones, unless they are prepared for the possibility of fracturing their natural hormonal system.
BTW, I tell guys that all the time. ^^