Weak/strong stimulants seemingly can be used back to back frequently. This is incongruous with the other consumable stimulants/depressants, such as drinks and pipes. This gives them an outsized value. You should be forced to wait a little while, on par with consuming one unit of drugs via pipe, before you can suck up more stimulants. This current situation kind of makes weak/strong stimulants stand out as an emergency fatigue button where all other drugs don't work like that. They also dont cost anything to use, opposed to drinks (container) or dried drugs (pipe) so one possible solution to my concern here would be adding a Drug Paraphernalia item, maybe crafted with Scrip (rolled up bill) that you need to use the powdered stimulants. In real life, there are limits to how much your mucosal tissue can absorb at any one time.