Over 2.5 years averaged about 70 hours a month with less during training months. I know if your out for 17 days you should get more than that, but the schedulers always find a way to put a day of R1 at the beginning and/or end, plus the lines don't always start/end with full days, so you just get partial rig for those days. Over that time, actual flight time exceeded rig only once or twice, so plan on rig unless you are planning to work open time.