Not if you're trying to save RAM (and operations to fetch said data) by storing stats per day. You'd need all stats to be per-hour in order for it work for any timezone.
They can't in their (Disqus) case because they're aggregating all the stats per day into a single value. I guess they could do it 'per account TZ' since the account name is in the key, but that means TZ calc on each write (not that that will make a huge difference in perf).
For a generic solution with easy TZ calc, you need to aggregate your stats into hourly values instead (or half hourly if you care about those wacky non-aligned timezones). The increased fetches don't matter because you can just mget them.
