Like insulin your results will taper off to just about nothing with continual use-more so with the B-12.
You'll notice if you take enough of it long enuff your urine will be red or dark indicating rapid excretion without absorbtion.
The body has more than enough B-12 after a few weeks of injections-and it stores it and it takes a while to deplete it.
Unless you are a vego, you will get plenty from a regular bodybuilding diet.
I am almost tempted to say "cycle it" but people will say I am full of shiest anyway.
I would say don't waste your money but it's dirt cheap.