That's longer than I do. I use the carries more as a strength builder. I prefer to go heavier for shorter distances. A good rule of thumb is to use regular lifting sets as a base and using the 1 rep = 30 feet equivalency.
For example when lifting for strength we normally recommend 1 to 5 reps... so when doing carries for strength and some size 30 to 150 feet work best.
For size 180 - 300 ft, so you are right in that zone.