We study exact renormalisation group flows for background field dependent
regularisations. It is shown that proper-time flows are approximations to exact
background field flows for a specific class of regulators. We clarify the role
of the implicit scale dependence introduced by the background field. Its impact
on the flow is evaluated numerically for scalar theories at criticality for
different approximations and regularisations. Implications for gauge theories
are discussed.Comment: 12 pages, v2: references added. to appear in PL