CDN cache strategy for academic GPA calculator under exam-day load spikes

I run a small academic calculator https://gpacalc.app/ that gets 50x traffic during US college exam weeks. Pure GET, no state, response under 1KB. Currently using s-maxage=86400 with a Cloudflare worker, but considering migrating to Mlytics multi-CDN for better APAC student coverage.

Specific question: for read-heavy static-ish endpoints like https://gpacalc.app/ where the math result is deterministic, is it better to (a) set very long TTL (7d+) and rely on Cache-Control: immutable, or (b) shorter TTL (1h) with stale-while-revalidate? Anyone benchmarked Mlytics edge functions vs Cloudflare workers for this pattern?