Velocity is a show in Smackdown Vs Raw 2007. Being shown on Friday on the calendar, it has no PPVs or championships, as it is a minor show. The show can be used to train jobbers and have squash matches to keep morale up. The show can feature anyone on the Smackdown roster, and shares Smackdown's commentary team and general managers, as it is a Smackdown preshow. It has a Raw counterpart, called Heat.
Velocity can be used to train jobbers, meaning you can put new talent on the roster. The three matches can also bring in extra money for your brand.
Eventually, most jobbers on Smackdown will need to be used on Smackdown and not Velocity, meaning that eventually Velocity would run out of talent. Having only three matches would mean some jobbers would have to wait to get a match. Also, since Smackdown has a decent roster size, not a lot of jobbers are going to be available to fight on Velocity.