TreasureHUNT!! operated on mostly page-a-week updates, so I think the average panel count was around... 5-6 probably?
The comic I'm working on now... it's kinda too early to tell lol. It's vertical scroll format, but the length also fluctuates a lot based on the episode content. Like, the premise is that it's a slice of life based on a D&D campaign I'm currently playing, so some episodes are pretty quick if it's just telling a single joke or scene, but some are more plot heavy and thus lend themselves to longer strips.
I think the shortest so far is like 12 and the longest is 36? So maybe average of 20 panels? xD