Great questions @christofkaelin !
I see we didn't redirect our old Boost blog to the new page, but you can find that introduction here:
Your schedule makes sense and I think this is a great way of using Flow.
With regards to the long-term effects, I can't say for certain that with a low dose (2x per week) that the same effects hold. For instance a study with CPD-Choline administered it 1x per day (at 500 and 250mg, and placebo). http://file.scirp.org/pdf/FNS20120600007_87495447.pdf
But most effects are more immediate/short-term (e.g. like feeling energized after drinking a cup of coffee).
For me personally, I use it every workday