I always go for at least 75 pages and usually 100, card stock so finders can turn the book over and stamp on the backs of pages from the back of the book towards the front. But I plant boxes on vacation in places that I will never return to visit or maintain, so the idea is that the log book must last the life of the box. I've only had a couple fill up, as far as I know, so for a maintained box that's perhaps more pages than necessary.

Depends on size of my box, combined with how frequently people are boxing in my area. I average 20-30 pages per logbook. Seems that in my experience, that's about when they start to get old enough and out in the elements long enough that, even in a tried-and-true LnL, they need to be replaced anyway. Sometimes the seal is compromised if the inside contents are not tucked all the way in, etc. and all it takes is ONE person doing that to allow moisture in to damage the logbook. I also use a ziplock bag for double protection but over the years they also get less effective and can leak. In a perfect world, a LnL box with room for a thick, chunky logbook, that would never go missing or need maintenance is our ultimate dream...but I wouldn't waste all that extra logbook material on my fantasy!

yes-this cemetery is a letterboxing-mecca and gets lots of visitors. I recommend that any boxer planning to hunt here take replacement pouches or boxes and plenty of extra, small logbooks and ziplocs because there are always many boxes in need of maintenance. Local boxers, bless their hearts, are helpful, but all that work shouldn't always be on them, IMO, and many planters are from out-of-town anyway and have trouble doing their own maintenance (like me!)
Be sure to go here-and AQ me so I can go with! LOVE Spring Grove! :-) There always seen to be around 100 active boxes here at any time.....some go missing but others keep being planted. Hey, Ohio friends! When are you planning another event at Spring Grove anyway?