I’m not 100% sure what you mean. Systems I have used that do this don’t generally store each time series in a different table. Normally there’s just one big table for intraday time series and one for daily, with columns being like ts, as_of, series_id, value, metadata or something like that.

It scales just fine depending of course on the usual stuff - load pattern etc. If you want really high scalability you should be using something like clickhouse anyway.

Edit to add: the rationale behind having separate intraday and daily time series tables in those systems is the type of the value and as of timestamps is different (in one its a date, in one its a datetime), and storing dates as datetimes is a rich source of bugs.