Start with time, not volume
Choose the number of viewing sessions you realistically have during the week. A watchlist built around four available hours is more useful than one that collects every interesting trailer and release announcement.
Use three simple lanes
Keep one title for immediate viewing, one slower or longer title, and one flexible backup. The first lane satisfies current interest, the second gives the week some variety, and the backup protects the plan when a title is unavailable in your region.
Record the useful details
For each title, note the official platform, region, format, runtime or episode length, and whether the title is confirmed available. These details help a watchlist become an actionable plan rather than a collection of names.
Review it once a week
Remove titles that no longer interest you, verify availability again, and carry forward only what still fits your time. A small, current list will always be more useful than an unreviewed archive.