It's like anything else. On average the LSD today is less strong that the stuff from the 60's and 70's. But that doesn't mean that there isn't good stuff around.

The quality varies wildly, but the solution is to just take more. That is why you hear about people taking 5 or 10 hits at a time, instead of one.

But, if you take 50(half sheet) of todays LSD, you are in for a trip. 70's acid, 90's acid, doesn't matter. You're in for it.

A 10 strip of today's stuff will bring most newbies(98%) to their psychological knees.

On another note, the marijuana today is exponentially stronger than the marijuana of the 60's and 70's. The stuff your kids smoke today is barely even the same drug as the hippies smoked during the Viet Nam era.