Fly Sparging a Partial Mash

I really don't want to get into the relative merits of batch vs. fly sparging here (I have read all the threads on that debate). Rather I am seeking advice from the fly spargers on how long I should expect a sparge with only a few gallons to take.

I will be mashing 5# of grain using a 1.33qt/# ratio. I then plan to sparge with 2.25 gallons. I assume 2.25 gallons will not take as long (nor does it need to) as the 7+ gallons I would use if I were mashing more grain.

Anyone know a ballpark of how long I can expect this sparge to take? Or how fast is too fast?

I try to plan for a 2 hour fly sparge with 15 gallons. Given that sparge rate, 2.25 gallons should take 18 minutes.

Thanks Yuri, that was what I wanted to hear!