It's a purely arbitrary number, arising from the choice of an 80/20 division of CPU cycles between exploring and exploiting. You have to choose some number; pre

It's a purely arbitrary number, arising from the choice of an 80/20 division of CPU cycles between exploring and exploiting. You have to choose some number; pretty much any choice would work more or less equally well here, though there is a sense in which 2 would be the simplest/most natural choice.