Most per signup programs already have a volume payout bump worked into their plan.
With a partnership program I would ask for a bump if I was sending 10 or more per day. (This assumes of course that they're not already giving me a bonus in other ways, like hosting me for free or hahaha giving you an employee to submit galleries or something, in which case you already have your bonus and I wouldn't ask for extra until I got to 20+ per day)
