Months of supply is the number that actually describes speed at a market level. At 1.63 months, active listings would clear in under two months at the current pace of sales if nothing new came on, which is a tight market rather than a slow one, though any single street can behave differently from the citywide figure.
Condition and pricing accuracy explain most of the gap between a fast sale and a stalled one. A home priced from a hand-reviewed valuation that accounts for actual improvements attracts serious offers early, while one priced from an online estimate that missed a renovated basement or kitchen either sits or takes a slow price correction.
Marketing exposure in the first two weeks also matters more than most sellers expect, since that window is when the most buyers are watching. Get your hand-reviewed valuation from Joel Dyck.