I would say 4 hrs is about how long it lasts for me too, but I never notice getting tired after. I only dose 1 pill at a time with stimulant/fat burner at work, or alongside my PWO as a "feel good" booster. I would probably take more, or a higher dose of Vicaine, but I like to have the bottle last a while.
I have taken it with IGNIT3, OxyMax XT, Pyroxamine, Cannibal Inferno, BloodShred WAR, Alphamine, Enduralean, OG Detonate, OG Norcodrene, Lipodrene Elite, Hydrazine, Finaflex PX Ultra, and now DS SuperStim (finally receive it-not bad!). All of the above, with or without a Bronkaid...
I think a lot of people would appreciate the synergistic affects obtained from combining it with Pyroxamine or Finaflex PX Ultra as they share a few of the same ingredients and could very well increase your mileage from Vicaine.