Looking at the code http://logback.qos.ch/xref/ch/qos/logback/classic/turbo/ReconfigureOnChangeFilter.html it seems like the reconfigure stuff is checked at every 16th logger use.
Wouldn't it be better to save the timestamp of the configuration file, and instead of number of invocations, measure the time since last reconfig, and check the delta until "now", and if it has passed, check the file timestamp again if it is newer.

In a busy application 16 log statements will be called very often, so by using a period of let's say 30 seconds would save a lot of checking?