I believe there IS a difference between northern hemisphere and southern hemisphere tubes.
Based on their manufactured convergence and degaussing with respect tho the earths magnetic fields.
I've never been sure whether this is so, or if it is an urban myth.
If it is true, it probably is only valid for delta gun tubes.
Trinitrons & their clones have a lot less ironmongery inside.
In any case, CRT TVs degauss every time they are turned on, & it works well.
If you leave 27 inch Sonys close to large magnets like those on TV Studio floor monitor speakers, the purity suffers.
I was getting called on to degauss them regularly, until I realised they were being left on 24/7.
Making it my mission to stroll through the studio & turn them off soon reduced my manual degaussing callouts to zero.