There's some evidence that carefully chosen synthetics might convey useful priors, improving convergence speed, generalizaiton and final performance.
Just the other day this was posted, for example: https://news.ycombinator.com/item?id=47388293
Just the other day this was posted, for example: https://news.ycombinator.com/item?id=47388293
Again, though, if those work I assume they will be used for the slowrun. Surely a few hundred LoC to generate data would not be considered cheating :)