As you will no longer be bidding for a line, do you think you will be able to bid for days off as well as trips? My understanding of the existing and proposed systems is fairly basic.
TBH your understanding is probably as good as mine.
I suspect that if JSS is adopted it will be a case of keeping preferences simple and not trying to combine too much, especially whilst junior...I suspect asking for SIN trips only
and being home Sat and Sun might not be the best tactic to employ initially....whereas bidding for "any trip, any day" might just work...
Like most things bidding wise I suspect you'll get what you want as long as somebody senior to you doesn't want it........and that ultimately the company will re-jig work and ignore preferences in order to cover the work........