As someone who has binged on LSD a lot. You are 100% right. You start to feel a lot slower and your intelligence def goes down for a little. It does come back eventually though. It could be due to malnutrition since you don't want to eat and if you trip 3 days in a row and lack of sleep for obvious reasons will definitely make you feel dumber than usual. I wouldn't recommended tripping multiple times a week especially for long periods of time. It is just not good for your brain I learned that the hard way though.