In my case, notice, I said, "MY" case, I too was hired as seasonal. Quit my job, took a cut in pay, with the only promise of, "If you do well enough, we may hire you back after peak".
OK, being in construction, running heavy equipment, I was used to being laid off all winter and if not hired, could just put my name back on the union board.
After peak, I was laid off 1 day and called back, gained seniority that day and lasted for 32 yrs.
Of course, that was 44 yrs ago. I understand things may have changed. If so, please refer back to my first sentence