I don't secondary, but if I did I wouldn't bother with it. I'd just give it a blast of CO2, but you might not have that option. Depending on how long your primary is though, there might already be enough going on to purge it anyway. I don't think what you're doing hurts necessarily, just adds risk of contamination with questionable rewards.
But anyway, I think you should examine why you are doing a secondary in the first place and if you really need to. Many of us don't feel like it adds anything to most beers.