Enquanto a varinha escolhe o mago, um conhecimento de wandlore pode ajudar a prever qual varinha escolheria qual assistente.
Tirando notas de Olivander sobre o assunto:
In my experience, longer wands might suit taller wizards, but they tend to be drawn to bigger personalities, and those of a more spacious and dramatic style of magic. Neater wands favour more elegant and refined spell-casting. However, no single aspect of wand composition should be considered in isolation of all the others, and the type of wood, the core and the flexibility may either counterbalance or enhance the attributes of the wand’s length.
(Pottermore - Wand Lengths and Flexibility)