sbws: weight bandwidths based on the time since the last bandwidth
Split off #27346 (moved):
weight bandwidths based on the time since the last bandwidth, because:
- if we only record bandwidths when they change, bandwidths that are updated soon after the last bandwidth are weighted too high
we can either:
- record the bandwidths every hour, even if they haven't changed
- weight each bandwidth by the time since the last bandwidth