Obviously, no label is paying any artists $250k "every two months," or any other figure based on time -- because it would be less profitable for the artists to take longer to release material (they could get paid to do nothing rather than record the required albums).
BUT, to say that no "contracts" are written on one sheet of paper may not be entirely correct (I know THIS ONE is fake as hell).
I was just reading a paper written by producer Steve Albini (he engineered Nirvana's "In Utero" album, and a lot of other rock records) about the rock record industry in the 90s. He said that a lot of bands got signed with "contract memos," which is basically an agreement to sign a contract with a label.
Obviously, there's nothing about money on a normal contract memo -- but they ARE legally binding between the artist and the label. Essentially, a contract memo binds an artist to a label BEFORE the contract terms are agreed upon ... which, if you're keeping score at home, totally fukks the artist, putting them in a position where they have no choice to get raped by the label for the agreed upon number of albums (or remained unsigned, as any other label would have to pay off Label A before the artist could release anything).