I can tell you that for me as well for many of my freinds in the biz. It is easier and faster to have the gun on the side. I have tried it both ways because I can. I did a bank drive thru on waith the surface cleaner and stoping to get the gun at the same time. Then on the next bank I just went over with the sureface washer and then came back with just the wand for the finnal rinse. It took longer to do it with the wand. That is what I foun out when I tried it. I am always trying to save or cut down on time. I found this to save a few minutes. I am sorry I don't rember the exact amout of time it saved but it saved time.That is my last two cents about this subject. I guess ut comes down to what you like , but for me the gun on the side saves time.