Snowflakes 3 and 4 have the same centre ring with inward facing cloverleaves attached to it, but different outward facing rings. Snowflakes 5 and 7 are different again. Instead of all rings or all cloverleaves in the middle, these 2 designs alternate a single inward ring with a cloverleaf. That presents a problem. Did you notice it?
In these designs all of the rings have been the same size (3-3-3-3-3-3 for a total of 18 stitches) A cloverleaf has 3 rings and it's bigger than a single ring. The middle ring of a cloverleaf is taller than a single ring of the same stitch count.
Take a look at the picture of Snowflake 3 shown here. A line has been drawn through the cloverleaf showing where it joins to the cloverleaves on either side. See how that connecting line is below the base of the middle ring? If the cloverleaf with the line through it is removed and replaced with a single ring, something has to be adjusted. That single ring will have to be much larger than that middle ring of the cloverleaf in order for the cloverleaves on either side to join to the centre of it.
You can see snowflakes 5 & 7 have alternating cloverleaves, and larger single rings (3-3-3-3-3-3-3-3 for a total of 24 stitches). This allows the joining picots of the cloverleaf to join to the second and sixth picot of the larger single ring.