I have not seen an if-needed YS work for me yet. Sounds like maybe some people have them to work but that seems to me to be more luck than skill. If you’re relatively senior and want a specific time slot you’re better off just YS first in sequence with the single time listed. NB is still getting max SC, so I assume WB is too. Track your reserve availability list for a week or two to see how your specific category is being treated.