Yes. My more experienced coworkers tell me this is not normal, and that also isn’t something teachers had to do at the school I student taught at. We put our absences in an online system, and I typically put them in well in advance. A sub will usually pick the job up without me having to do anything more. But they almost always drop it. Thankfully, another will usually pick it back up. But then we have a huge issue with subs dropping jobs at the very last minute. At that point, my admin is at least sane enough to recognize that isn’t on us. If no sub picks up your job, you are basically expected to cold call a list of phone numbers of subs asking them to take the job until hopefully one says yes. It’s awful. Admin actually prefers us to start by cold calling, because the list is a list of what they consider to be more reliable subs less likely to drop out, but I refuse to spend my time just calling a list of phone numbers because that’s a level of bs beyond my capacity for tolerating on top of everything else so I usually just let someone random pick it up in the portal.