Well, the idea is that you take meth daily so you can be a productive worker - it's a great idea but you might want to re-consider using meth on a regular basis as once you get used to it as a tool for work, it's hard to go back to work sober..
But it's an easy thing to control when it comes to addiction - if you get "urges" to use more then you shouldn't be using in the first place.. after I moved back from the coast (where I was badly addicited to it) I got a job that started early in the morning, so from time to time I would start my morning with meth - I never got the urge to do more and I used to be addicited.. so I think someone thats never had a problem with it wouldn't lose focus because they are fiending.. also, a small dose taken orally will give you a fair bit of energy - don't under estimate that.. you might not be rushing the same as right after you rail a gagger, but you wont be thinking "maybe I should do just a little more, I had a blast last time I was at Kandie Land 6 listening to Paul Oakenfold after I did that glass" .. you might even be an annoying asshole with too much energy - the type that doesn't shut up to fellow co-workers..
I was never productive, meth made me productive, but after I was hooked for a few months (then I quit) my life was totally devoid of meaning.. to this day I cant stand to be sober, I have to be on something... so it's not that meth use made it impossible for me to become productive - I never was in the first place.. it just gave me something to compare my lazy sober lifestyle too.. also, just to remind everyone, I was shooting like a 1/4oz of high-quality meth daily (well, per 24-hour block) .. I abused the drug in ways you will never abuse it, so don't think I was a casual user that got hooked - I had nothing better to do so I used daily, then when I finally ran out a few months later, I was addicited.. it's a very easy drug to control, nothing like what people make it out to be like...
Again, it's not physically addictive, so as long as you have a little will-power, you will have no problem ... trist me on this one, even after I was addicited (and quit) I used it to have productive work days about 1-3 days a week for the entire time I held the job (only a few months before I quit - they wanted us to be there at 8am!)