In my experience, it's not the case. I tried periods when I drink coffee, and drink no coffee for months. I was much more productive when I did drink some coffee.
P.S. Of course it's a sample size of one.
P.S. Of course it's a sample size of one.
Although my most productive periods have been those days where I start drinking coffee again after a month of no caffeine. Then it tapers out but remains at a higher baseline than no caffeine.