Katakana long mark written wrong

Would someone still be able to read katakana if the long mark was written horizontal but the other symbols were written vertical (above and below the long mark)?

I know it's not the correct way to write it, but would people still be able to make sense of it?

Japanese people (including myself) would "recognize" it and figure out; it is simply wrong writing, though. I would probably think, whoops; a good try :)

understandable but a bad habit that should be broken asap