Ah yeah, I've been playing a little of your pack Ski-Sloping Lemmings, and that frequent use of vertical scrolling immediately stuck out to me!
Then again, I thought that was on purpose to simulate the idea of Lemmings going down a mountain / ski slope on almost every level. So I wasn't sure whether this was your level-building style in general, or just a creative decision you had taken for this pack specifically.
Sadly, the Groupie rank in Lemmings World Tour is already completed - by this point I'm pretty sure I'd be able to create a level in your style...
I could do something like a Groupie rank again in another pack, of course - the reception of that rank specifically was very positive, to say the least, as far as I could tell. I have a couple of ideas for more levels dedicated to other forum members - not enough for an entire rank, least of all a separate pack, though...
Apart from you, I understood most of the other users who commented here in a way more along the lines of "only use vertical scrolling when necessary". I'm not sure whether avoiding doing something for the sake of it is just part of the general idea that you shouldn't include anything in a level just for the sake of it, or whether it's something specific about vertical scrolling that makes it a "necessary evil" for levels that do require it, but something that should be avoided otherwise?
Oh, and I love to make levels that are exactly 1 screen in width, but then have a larger height.
Yes, those I also like quite a lot, indeed!
One specific positive example that comes to my mind is "The Octathlon" from Lemmings 2 in the Sports tribe. The main issue with this is the variable definition of what is 1 screen in width - my screen seems to be wider than the average, which is why I practically never use the default width of 320 pixels, because that always leaves ugly grey spaces on both sides. The level height, in contrast, seems to be sized automatically in such a way that you don't have to scroll up or down to see everything in a standard, 160-pixel-height level, at the same time as not leaving any grey borders at the top or bottom.
I think what we can take away from this is that having to scroll into two directions simultaneously is more annoying than having to scroll only either left/right or up/down.
But if I create a level that's exactly one screen width on my computer, i.e. not horizontal scrolling required, and instead include vertical scrolling, someone with a narrower screen will still have to scroll in both dimensions when playing that level, thereby destroying the feeling of such a "one-screen-width" level.