No different to any other substance, you build up a resistance and have to either increase the dose or switch it up.
It kinda capped out after a few weeks, and I'd basically just keep it rolling until the desired effect was reached. It was a pretty ridiculous amount, but wasn't a particularly expensive habit to maintain. /richkid

OFC this is the 90s we're talking about when rave culture was at it's peak in the UK & the corresponding drugs were not only cheaper - you didn't have the worry of getting random crap tossed in (unless you were a smack-rat).
Hell, even Ecstasy was guaranteed to be MDMA rather than the current lucky dip of caffeine, amphetamine & if you're lucky MDMA.
It was a very different time for drugs.

But yeah, IMO everything in moderation; unless you've got some serious wallet to back it up lol.