N.K.
I think it definitely depends. However, if you're pumping, don't forget to add in all the extra time for cleaning parts, making bottles, storing milk, etc. One shortcut trick is to store the pump-setups in the fridge between pumping sessions--you can just wash them well or sterilize once per day, and keep them cold in between sessions. Saves a little time. I also remember reading that a pump session really isn't more effective past 15 minutes or so--basically that you'll get about all you're going to get in the first 15 minutes. Search www.kellymom.com for details about this.
Adding: Also consider that just pumping doesn't feed the baby--it can still take the baby up to 15-20 minutes to drink the bottle. Once you add together pump time and feeding time, that could easily be over 45 minutes.