Priority and import precedence

It seems the priority attribute on a template is of less importance than
the order in which stylesheets are imported, when using
xsl:apply-imports.

For example, if stylesheet A imports stylesheets B and C (in that
order), templates in B will always be selected over C regardless of
priority.

Is there a reason for this?  (It seems strange as usually the 'one that
comes last' selection process is the last resort, not the first)

cheers
andrew