Yes you can, I have. It may be because I'm not a fan of uppers and prefer downers(opiates,benzos,soma, and know it's not a downer but weed.) First time I did it I did half a gram by myself. I smoked a little, snorted a bump, then shot a bump,lol(don't do that, it was low doses of each but I wanted to try every way) I continued and finished the gram after I left my friends house felt awesome blasting music and cleaning..no bad comedown, I never have bad comedowns on Meth, Coke is a different story. I've done it a number of other times here and there, mostly I shoot because smoking is sooooo FIENDISH. Planning on getting some soon, it's been forever, but I do it for a day, usually am still going the next day then sleep. I remember a friend brought me about 10 dollars worth for free, had to go to work early, smoked it and got like 3 maybe 4 hits and was good, slept that night.
Thing is you just gotta be careful. It is addicitging and when I was 21 I'm not gonna lie I would go on Adderall binges for a week. Would get my script of 60 and go and go and go. I can't imagine doing that now,although I see how some people would. Just be careful, it's a very good feeling, but not as good as a shot of Morphine, Oxy, or Dillies! And don't shoot if you don't already, I wish I never started that shit.