Extending the courtyard would lead to much bigger courtyard area. imagine a CAPC2020 extended 25% only for those 0.0001% and this happens in huge mass production.

What more concerns is the extended required clearance around the pad due to 25% side overhang as solder mask is not an isolation and the overhanging pad distance to copper of a different net underneath the component pad would be a clearance error.

The IPC 610 has a "Note 1" underneath the table for almost all component type.

something like "the minimum electrical insulation distance is not violated" I guess that is the escape path here :-)

Now the IPC also says something like copper tolerances round about 20% if the pad width is reduced by 20% then the component will have a side overhang and that is accepted but the nominal clearance between the pad / component and the surrounding copper of a different net is not violated.

I currently assume that the IPC 610 25% value takes into account the IPC copper tolerances of 20%

a component completely moved 25% is only accepted when isolation is not violated.

This IPC note 1 could mean if isolation is violated, side hangover is not accepted.

Side overhang is less or equal to 25% width of component termination area W or 25% of land whichever is less

Note. Class 1 or 2 is 50%, to strive for is no side overhang

for a capc1005 the 25% leads to max 0.15mm what is equal to the courtyard excess of 0.15mm for density level N

Am i right?