grain crush for sparging techniques

I apologize if this has been asked before, but I havent been able to find the answer. Im curious if the grain can or should be milled differently for different sparging techniques (fly vs. batch). with batch sparging a stuck mash is less of a concern right? so can the grain be milled finer? if this is possible will the finer crush result in higher efficiency, maybe offsetting the losses associated with batch sparging?

I have mainly fly sparged, having only batch sparged once, but I would think that you can still get a stuck sparge with batch sparging. After you add water and stir, you still have to vorlauf until your runnings are clear and drain the grain bed. At the point that the water gets close to or just below the top of the grain bed, I would think you would risk compaction if your grain is too fine (although at this point you are close to being dry and needing your next water addition any way). Also, you are draining faster since you don't have to match flow rates and I would think that the faster draining would pull the grain bed down and cause compaction if it was too fine. I do think it is not an issue since if you get stuck, you just add water and stir again (your going to do it any way, now it is just a bit early). With fly, you want to set the grain bed and maintain it.

Like I said, I have limited experience with batch sparging, so this is mostly an educated opinion with a bit of experience. I could be completely full of it as well.

You will hear many batch spargers claim that it is hard to get a stuck sparge when batch sparging and that it is OK to mill finer. I am not sure this is entirely true. However, there are a couple of reasons that could support this idea. First, many batch spargers use a stainless steel braid to filter the runnings from their mash. These tight knit braids definitely do a good job of filtering fine material (like bits of husk), so you might get away with a finer crush if you use a braid. Second, fly spargers must be very cautious about channelization and compaction of the mash while sparging, because it can affect efficiency. Batch spargers have no such concerns. In fact, if you do channelize when lautering the mash, it might actually help to prevent a stuck sparge.

I do not fly sparge, so I can't speak much from experience. But I do know that I have done recipes with a relatively fine grind from a cheap Corona mill (eats husks) using up to 50% wheat or large amounts (>30%) of flaked rye or oats (gummy, gummy) and never have had a stuck sparge. I don't use rice hulls, either. I suspect many fly spargers with false bottoms would get very scared to try that.

However, batch sparging is far from immune to stuck sparges. I certainly don't mean to imply that.

I have milled my grain increasingly finer over the last 3 batches to experiment with efficiency, and have found little difference, I batch sparge.