Can layout, orientation, or item sizing strategy affect how CollectionView items render or when events are triggered?

Yes. The layout (Linear or Grid), orientation, and ItemSizingStrategy (MeasureFirstItem, MeasureAllItems, or Fixed) influence measurement and item realization. Predictable or fixed sizing is recommended for heavy feeds to reduce layout recalculations and ensure consistent event timing.

<CollectionView ItemsLayout="VerticalList."
                ItemSizingStrategy="MeasureFirstItem">