[wim]

folks bear in mind that tests are made on brand new zooms at the peak of their performance the question is how long will they maintain this performance

When you treat them well enough, they will maintain their performance.

Kind regards, Wim

[mst]

Yep, my experience, too. The especially mechanical wear you can sometimes find on under-engineered lenses is mostly affecting moving parts for zoom and focus, but not the alignment of elements... unless, of course, we're talking about cheap and flimsy optical stabilization elements But for those, the risk is higher that they're misaligned brand-new already.