What you see there is just my Russian contingent. I (usually) only use one crew per two tanks (or less because I can only play one tank at a time!), one premium and one regular. A premium crew can jump to another same nation, same type tank with no penalty and back again. Thus, each day I'll train a crew (usually x2 experience), jump tanks and train it (x2) again. Thus, two wins gets my one crew x4 experience not counting the 50% crew bonus for training in a premium tank. Slick huh?
Have to give Nort some cred for putting me onto this.