You aren't skipping the 4th stitch... the ch 1 essentially acts as the first sc of the next row.
If you don't count it, what will likely happen is that you'll end up increasing your work by accident.
You have to chain up once stitch to make the next row lay flat. If you were doing a row of dc next you'd chain up two and then do a dc. If you were doing a treble, patterns either have you chain up 3 or 4 and then do a treble. [note: European and US patterns use different short forms for half-treble and treble stitches].
You can opt to not count it, but you will find on doing a rectangle that every other side of your rectangle will have a little loopy on the end of the row where you've flipped it over...
if this isn't making sense, as it really is a visual thing I'd be willing to make a mini swatch. I still have to post my other picture for the kniting thing I promised.