Hey Tristan (namesake of my brother!). JS Bin was definitely a work of love at one point, and I believe will be again, but I definitely prefer bouncing between projects. I keeps my tools sharp.
Right now I've been doing a lot of node development particularly for the CLI and I've learnt tonnes about testing and streamlined workflows (which I'm intending to create into a video series - which, is another one of those projects).
So really: I like to juggle my work as much as I can afford to.