The locals we sell to around here generally, don't allow rolls outside of one marketing year, but yea, made some coin rolling till we can't and at times could of made quite a lot with indefinite rolls. Made some extra rolling backwards once too, when the market went inverted (2012 ?), picked up extra on spread and basis that time.
      Old adage I've never forgotten "when there's a big carry (meaning big carryout bushels) sell the carry." Rolling after that sale has same effect usually, for awhile anyway. HTA's only way to accomplish it, far as I know.
Roll was worth an extra dime on corn after fees from Dec to Jan Delivery here this year, maybe more at some point. I'll always take that if cash flow isn't an issue.