Left front yoke

Cast on 7 sts. Purl next row.
Next row: RS K1, M1, k5, M1, k1 - 9 sts.
Purl next row.
Next row: RS K1, k7, m1, k1 -11 sts.
Next row: S1 purlwise wyif, p3, k1, p6.
Next row: K6, p1, M1 p-st, pm, k 4 - 12 sts.
Next row: S1 purlwise waif, p3, k2, p6.
Next (inc) row (RS) K6, p to 1st before marker, M1 p-st, so marker, k4 -13 sts

Working in pattern as established, (k the knit sts & p the purl sts) and rep inc row every other row 7 more times, every 4 th row twice, then every other row twice, end with a RS row -24'sts.
Next row: S1 purlwise wyif, p3, to last 6 sts, end p6 place sts on holder.

I really don't get this. Do I continue knitting the 8 rows knitting the plain & purl sts until there are 24 sts. This will not be very long cause I am M1 with almost every row, if I continue the pattern of 8 rows. How many rows would I have knitting until I reach 24 sts.? Do I only knit the inc row and alternate 7 more times.
What does every 4th row twice mean, do I knit just that row twice. Also every other row twice, what is every other row mean.

Hopefully you can help me, I am an experienced knitter. This is a vest (no sleeves) but this has got me.

If this is the left front yoke surely it should run up the whole left front side.

Anne Knell