Does sbws need Tor to report observed bandwidths more often?

In #23856 (moved) in 2017, we updated the observed bandwidth to 5 days from 1 day. We should review this change, and decide if Tor should report observed bandwidths more frequently.

In #28983 (moved), we'll work out how long it takes sbws to measure most of the network. We could use this time as a guide: Tor probably shouldn't report observed bandwidths faster than sbws can measure them. But Tor should report observed bandwidths every few times sbws measures Tor.