Dutch former underground arstist turned Duck writer (among his many acomplishments) Evert Geradts once told he he was a huge fan of Blondie, mainly because when he was younger it was reprinted in his parents' tv guide, De VARA Gids. I understand, but as far as I am concerned they reprinted it in the wrong format. Like all strips that started before the war, Blondie used to have a full page of it's own, one third of which was filled with a second strip, Colonel Potterby and the Dutchess. It was a pantomime strip in a totally different style, somwhere between Chic Young's own Blondie and Otto Soglow's The Little King. I would have thought that this strip was the work of one of Young's assistants, but most online soures credit it to Young himself. Maybe he only used assistants on Blondie (such as Paul Fung Jr., who drew all those dogs in the fifties strips). Samples of Colonel Potterby can be seen if you follow the link.
Although Potterby started as a half page strip, sharing the page equally with Blondie and Dagwood, it shrank to one third of a page in the forties. That is also, when some papers started cutting the two apart, sometimes running either or if both were used, never together. The remaining four tier Blondie was the original format in which the strip was drawn, but it had a problem: it ran two thirds of a page and that was deemed too much by most papers. So a new three tier version was made that only filled half a page. That was achieved by lengthening all the panels. And although it seemed almost natural, if you see the two thirds version it somehow fits better. Here are a couple of samples from the fifties, including one rare two thirds page one. Unfortunately, the paper I found it in was badly folded and I couldn't repair it without damaging the art, but I hope you'll catch the drift.
Update: I uploaded another two thirds one.
Update: and two more from the same period.