ddickinson: What if GOG had put each flash sale game on for just 1 hour, instead of 5 hours? Would that be a good compromise between the flash sale and insomnia sale? It would allow people to make the purchase, without being beaten or have the site crash, but would provide a faster pace for those wanting a faster paced game. They could even just show one game for that hour, meaning 24 mystery games each day, and maybe only a few repeats over the course of the sale. (Did the insomnia sale repeat games? Or was each game only shown once?)
As a compromise, it'd work somewhat, but the overall speed would still be lost. If you're looking to crank people's reactions up to higher levels, you need something faster, more of the risk of loss (which can then turn into either elation at beating the clock and getting the item, determination and a reason to stay connected to the sale through to the next round, or yes, all kinds of frustration).
Insomnia went for three rounds, three full rotations of all included items, for both the Fall and Spring versions.