DE FACTO....EXCELLENT Will try and find the Airworthiness ref documents which define this.
" Weather update
− before ETOPS Entry Point:
With the support of flight watch or by their own means, the crew must
make every effort to obtain weather forecasts and reports for ETOPS enroute
alternates.
Weather forecasts at the estimated time of arrival at the en-route
alternate airports must be higher than the normal minima.
NOTE:The ETOPS dispatch minima do not apply when airborne.
If weather forecasts are lower than the normal crew minima, then rerouting
is required, or turn back if no route at the authorized distance
from an en-route alternate airport can be used.
− after ETOPS Entry Point:
The crew should continue to update the weather forecasts and reports
for en-route alternates. There is no requirement to modify the normal
course of the flight if the weather degrades below normal minima.
As for a normal flight, the crew must make every effort to keep
themselves informed on the weather at the destination and the
destination alternate.
I believe it is the second area (after ETOPS entry point) where people are getting confused.