Modify system behavior after reconfigure

[Jone]

To run 'reconfigure' for minor changes to the system configuration
is inconvenient. For example, this option:

  (sudoers-file (local-file (config-file "/etc/sudoers")))

provides an easy way to make changes at any time. But what about mcron?
The user has a directory ~/.config/cron, but it cannot run system-wide
jobs. So the old way with /etc/cron.d/ still remains comfortable: let's
say I just don't know what tasks I'll need in the future, and add them
one by one - and each time after that run reconfigure.. no way!

I think the question is obvious?
(Forgive me for my bad English, but mostly I only read in this
language, not write).