Anyway, isn't it unusual to have 20+ km laps at the Worlds? I've always thought 20km was a limit.
Indeed.
There is no limit as such, but laps of 14-21 km are definitely the 'standard' in recent years. And going back further, the 'standard' was even shorter - 12-18 km.
I've looked at the last 40 editions (including the cancelled one in Aigle/Martigny), see the list in the spoiler below.
The average distance of a lap was ~16.3 km (allowing for rounding differences), and only five of those were longer than 20 km (Benidorm 1992 at 21.8 km, Madrid 2005 at 21.2 km, Salzburg 2006 at 21.7 km, Innsbruck 2018 at 23.9 km, and Imola 2020 at 28.9 km). This means that Imola is a huge outlier length-wise.
