Left: PWN extension evolution with time, in comparison to the modelling considered in this work. Right: PWN extension evolution with Ė, as fitted in the R_PWN(Ė) column of Table 6 for pulsar wind nebulae with Ė > 10³⁶ erg s-1 (see Sect. 5.2.1). The shaded range shows the fit range and standard deviation σlg R . 1 dex refers to an order of magnitude and is the unit of the logspace defined σ_{lg Y} . For clarity, this plot excludes PWN candidates and divides the sample into nearby and far pulsar wind nebulae to illustrate the potential selection or reconstruction bias (see text). The dot-dashed and dotted lines indicate the systematic minimum of 0.03° and the maximum measured extension in the HGPS of 0.6°, respectively, which are both projected to the average PWN distance of 5.1 kpc.