Veriable answer. It’s all timing of when one gets hired . If you get hired and on the line in time to hit summer than many junior guys become line holders right away due to block hour increase . PBI layovers on both the 737/320 fleets. The odds of a junior guy getting them on his bid as first choice . Pretty slim.

if one gets hired and on the line after summer things slow down massively , and many people getting put on reserve till flying comes back.