The other thing to watch out for on DL are multiple flights with the same flight number. As an example, DL369 is assigned to both LAX-ATL and ATL-MGA (with about 2 hour layover in between them, on different planes and usually requiring a terminal change). If your itinerary is, say, BNE-LAX-ATL-MGA you'll get credit for a BNE-LAX leg and a LAX-MGA leg (even though it is two flights).
Due to the same flight number on all flights, the LAX-ATL-MGA part of the itinerary will count as *one* leg of 2524 miles (straight distance between LAX-MGA) instead of *two* sectors of 1946 and 1483 miles. Which means you get a lot less SCs and points.
The MGA one is the one I personally come across most often in my own travels, but there are quite a few routes it happens on.
Something to bear in mind if you're counting on those SCs for getting your status!