I'm not sure on the valor ...

 Start it clean, keep it clean was the phrase.

The sales guy said this would extend the time before the second spray needed to be applied, keeping it cleaner, and possibly eliminating an in season spray in my small field that was in corn last year. 

I'm thinking now of not using it on what is coming out of pasture, but only in what is in corn stubble.  But I'm not sure yet.  If $9 of residual keeps it cleaner and saves a potential third spray, maybe it is a good move.

 Also valor supposedly to get a couple weeds that are harder to get with round up.  I forget which weeds, and don't know if they are even a problem for me. I guess they will push every product, but the residual may help, and beans are over $13, making the money easier to spend.