But there are still plenty of cases where the "correction" function, whether by Garmin Connect or by Strava actually makes the accuracy worse rather than better. The correction is done by looking at topographic data and if that data doesn't have the information about where there's a bridge, or overpass, or where the road builders smoothed out the landscape then the 'correction' will be way off. Plus the original topo data is also subject to measurement error and I can easily find places on topographic maps where errors were made.