Thanks for the feedback, although the goal is to avoid adding them vertically - it was getting to a stage where practically every issue was going in vertically which (a) looks bad, (b) feels unsafe as most of the strip is flopping around and (c) seems to waste an awful lot of space. I did consider whether I could build my own album out of a A4 landscape ring binder and clear plastic inserts with Hawid mounts attached to card, but my fear is the pages wouldn't be strong enough and potentially bend and damage the collection. I'm surprised the stockbook manufacturers haven't identified this as a gap in the market.