Estimate storage for video files.
Video storage scales with resolution and inversely with codec efficiency. H.264 at 4K needs roughly fifty megabits per second; HEVC or AV1 deliver comparable quality at about forty percent less. Editing proxies are a separate cost that many people forget — a five megabit proxy stream adds little per minute but applies to everything you ingest.
Master footage size
Master GB = base bitrate x (1 - codec saving) x minutes x 60 / (8 x 1024)
Proxy overhead
Proxy GB = 5 Mbps x minutes x 60 / (8 x 1024)
Around forty to fifty percent versus H.264 at equivalent perceived quality, and AV1 a little more again. The cost is encoding time and weaker compatibility with older hardware decoders.
For 4K and above on anything but a fast workstation, yes — they make timeline scrubbing responsive. They can be deleted once the edit is finished.