I've noticed a pattern, so I'll make a prediction and test it:

I've been consistently able to accomplish things on Tuesdays since roughly mid April. Only Tuesdays. Other than one recent Tuesday, which was just as blah as most days that aren't Tuesday.

I've been consistently eating bigger, more complicated meals on the weekends over the same timeframe, other than the weekend before the recent blah Tuesday.

Hypothesis: it takes somewhere in the neighborhood of 24-36 hours for the powerup to get from the food to my brain, but flooding my body with loads of food diverts resources to metabolism and reduces the impact (hence, 2011 wasn't all sparkles and sunshine even though I was actively trying to eat better in general that year).

Experiment: When possible (so the end of August), try rearranging the schedule (live on nuts and juice on weekends, feast on Mondays/Wednesdays/Fridays, etc), to determine if the effect is still in the 24-36 hour range. If it works, I have a means of increasing productivity by 250%. If it fails, update and try something different.