Candy, the only reason to do what you're saying is if you weren't really coming off in the first place, i.e. bridging.
Now in the past I've run cycles where at the end I'd switch my test from a long ester to a short the last 4wks or so and run an oral up to the end along with it, usually winny tabs, but this is differant then what you're saying. Even so, it's not a bad way to do things...a lot of guys do this and do so with success. Personally, I don't really do this anymore but it doesn't mean it's a bad thing.