Anything for the love quest, to him finding a boyfriend free girl was a matter of life or death so looking for one was the most dedicated we've seen him. So he was productive there, just unsuccessful .
Doing walk-a-thons for cancer research, donating to Toys for Tots, giving up time to help those less fortunate in soup kitchens.... Or standing up while playing Guitar Hero.
Not starting a bunch of threads that over-use an already tired joke.
More seriously, though, selling the medallions and sketches, and even the amiibos on some level. He's actually looking for a way to actively get something out of Sonichu, instead of just sitting around and hoping for money to fall in his lap.
In a serious answer I'd say its a toss up between 2 periods of time.
Right now he's producing several "products" and running a moderately successful Etsy. He's even printing up and publishing Sonichu.
I'd say the other most productive was when he was still actively drawing Sonichu on a regular basis.
Pretty much other than these two periods of time he's just fuckin around doing nothing at home or being awkward in public.