Yes, Place marker the first time (two rows) and slip marker the next two rows. Place when you need to add a marker that is not there (row 13 & 14 to get one near each end). It appears the markers are there just to remind you when the pattern changes for the border. The border is small blocks (four rows by 3 stitches) of alternating st st and rev st st while the center body of the blanket is large blocks (12 row by 9 stitches).
I think I’d place markers in row 12 and slip there after; one marker after the first 9 stitches of row 12 and another before the last 9 stitches. Then it is clear that you are changing from a 3 stitch repeat to the larger 9 stitch alternating pattern.
It is one of those patterns that is easier to see and understand than it is to describe st by st and row by row.[/color]