Are pre-built first-aid kits actually worth it, or should I build my own?

Across specialist subreddits like r/Ultralight, the dominant view is that pre-built kits from established brands are a solid starting point that you then customize, swapping in leukotape for blisters, adding personal medications, and removing items you wouldn't actually use. Pure DIY kits can be lighter and cheaper per ounce, but pre-built kits win on organization, waterproof packaging, and the included quick-reference guide.