'Mash Out' - Necessary step?
 

How many of you do a 'mash out' step? I'm still getting to grips with all grain having done just two batches, but in that time I've noticed that the water level starts to fall below the grain bed pretty quickly on my first runnings despite draining it at a nice slow space. I'm a bit worried about encountering a stuck sparge. Will doing a mash out make things a little more fluid?

I typically mash out when I'm brewing. I don't think it is always necessary, but when mashing with wheat or oats I think it is helpful. For most brew days, it probably isn't necessary, but I'm in the habit of doing it.

BTW, it also helps me get my temps back in line before adding sparge water if the mash temp has dropped a few degrees below what I was aiming for..

I've never bothered with a mash out.

I kind of do a mashout - I raise my sparge water to about 190F, which raises the mash to about 168. I find that it improves lautering. However, I don't think it's a necessary step.

A mash out will also stop the enzymes working. So, if you have a malty beer that you don't want to dry out, a mash out will stop them instead of having them still working on the beer during the whole run off. If you want a very dry beer, though, you can do the opposite, no mash out and the enzymes will keep going during runoff.

Me? I do a mash out at 168.

I mash out. It stops the enzymes and the heat allows more sugar to be dissolved in the wort.

I asked Jamil about this in Milwaukee at the NB grand opening and he recommended to always do one.

I do one, especially now that I crush my own grain (which means I get a much finer crush than when I used the mill at my LHBS). I've found that mashing helps with the runoff, higher heat = more fluidity

Doing a mash out step will help with repeatability in your beers. As others have mentioned, it denatures the enzymes and locks-in your wort profile. If it happens to take you a while to lauter one day, the increased lautering time will not effect your wort.

If you batch sparge, I don't think a mashout is necessary. Adding hotter sparge water for the first batch performs the same function without wasting time. Buffman suggested the same procedure.
If you are fly sparging, I think it is a good idea. I'm not sure which you are doing.
You mention you are worried that the water level drops below the top of the grain bed, which would suggest a fly sparge; but you then mention the first runnings which would suggest a batch sparge.

-a.