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Mostly depends on the size of pike you're on. A four footer while not unheard of is uncommon pretty much everywhere. I've landed hundreds of pike through an 8" hole over the years and only had a handful or so that were challenging (those, save one, were muskies) and one that just wouldn't fit at all. Larger holes are nice if your average size is mid-30" and up and a real plus if you've got over 20" of ice. Downsides to bigger holes are your tipups sliding down or making a hazard to step into later. Not to mention just toting a larger drill...
I have lost some nice Pike cuz I couldn't get their head turned up an 8-in hole.If I could have gotten his head turned I'm sure I could have gotten the rest of him up the hole.I have seven inch 8-in and 10 inch augers.And there is a time and place for each of them.Have I ever stepped in a 10-in hole? Sure but I don't blame the whole size I blame my own stupidity! Primarily because in my case that's what it was.I was shoveling out an area to put the ice shanty and had filled in the holes with snow and just wasn't paying enough attention.If you know the hazard is there because you drilled the hole yourself you can't blame the hole for you stepping in it!
Early and late season I use an 8" since the hole never freezes up. But mid season, I'll use 10" holes due to the cold. There's days the 10" hole will be an 8" in 2-3 hours and its worse walleye fishing at night in -15 to -20 degrees.