Platform playbooks: Instagram vs TikTok vs YouTube vs Pinterest

What wins on each platform in 2026, with a per-platform table (format, cadence, what the algorithm rewards) and a one-prompt 30-day playbook. Going deep on one platform beats a thin spread across four.

Every platform runs its own algorithm, native format, and buyer stage. Posting the same clip everywhere gets outranked by creators who play by that platform's specific rules, and burns a small team's time four ways instead of one. Pick one by AOV and buyer stage, then run its playbook for 30 days.