One entry, and it settles an argument about lighting that most museums are still losing.
A morning, not a day. Take the extra hours elsewhere.
Any season, and that is genuinely true here — the collection does not rotate for weather. What matters instead is the sky on the day you come. Overcast is not a disaster, but a bright morning gives you the glazes at full argument.
There is effectively no crowd. I have stood alone in front of the celadon cases for longer than is decent and nobody came to hurry me. It is the quietest good room in this directory and I would rather more people knew and it stayed that way.
One entry makes a short visit, and the sensible response is to go twice in the same morning rather than to pad the afternoon. The island outside is pleasant and entirely optional.