I only do 25mg of dbol a day, i don't see why 40mg is necessary unless your dbol is bunk. but to each his own. some guys have to run twice the dosage to compensate for poor diet/training. not saying thats you of course but its the case 90% of the time
if its a 4 hour half life then you should aim to take it atleast every 8 hours.
so if you do 40mg then do 20mg am, then 20mg pm.
and no if something is 4 hour half life it doesn't mean its only active in the body for 4 hours then magically is gone. once its built up in the system after 1 week or two it will take dbol a few days to clear out of your body.
to the OP, AAS isn't like taking a preworkout stim where you take it before your workout and magically get a boost. i think you should read more about half lives and how they work etc. AAS slow releases into the body, yes even orals which have 4 hour half lives, thats why they are so awesome .. they don't just work after you take them for your workout and then thats it. again, they aren't stims like caffeine that you take for a quick boost and then thats it