
a surface sector does use up a coupon.
Consider a paper ticket AAA-BBB/CCC-DDD
coupon 1 is AAA-BBB
coupon 2 is unable to be used since next flight leaves from CCC not BBB
coupon 3 is CCC-DDD
3 coupons used even though only 2 flights
That said, I count 23 nonstop flights + 1 direct flight (with transit) as only 24 coupons (assuming no surface sectors).