Never really thought of it that way. 3 Weeks is quite a short time when you think about it.
Considering I take migraines often that means around 3 or 4 of those days I wouldn't fly.
In addition, there is a big difference in US vrs UK weather. I would be flying in the UK, so perhaps learning in the UK enviroment would be best.
Although, when building flying hours, the US really is best then.