It's rare but it happens when a lot of senior pilots waive guarantee or take vacation. There ends up being a lot of coverage days and a lot of hours to cover and junior lineholders get screwed. I've been the most junior guaranteed line holder in base for about a year now and I've had everything awarded from a 63 hour line (with no reserve days added) to a 97 hour line. One of the times I got a 97 hour line I was able to drop a trip and ended up working 85. The other time I didn't have much to do that month and took the 97 hour line and the nice paycheck that came with it.

FWIW July is when I have the 63 hour line. My base is overstaffed and I've been getting nice schedules even being junior. It's not always doom and gloom.