I would say 3 to 4 day trips would be the exception and never the norm. The longer the trips the more use they get out of you. This is not the place to be if you want short trips. Your 15 day flex trips will 99 percent of the time be 5 days long and 18 day you can bid for short trips but the shortest I have heard of is a few guys (out of hundreds) getting 4on 3off but just for one month. Next month they did 6-8 day trips. Don't want to burst your bubble but just want to be honest