When installing updates, dracut is called multiple times to update the initrds
of all kernels, for example when lvm2 is updated or when the kernel is updated.

It would be better if the initrds were updated once at the end of the
transaction (as Fedora does it, for example).

Despite of that when keeping older kernels, there may be reasons _not_ to
update the initrds of the older kernels:

First, some may be removed on next boot anyway, and second, more important:

If the idea of older kernels (and initrds) is to have a failback in case the
new kernel, initrd or and binaries inside are broken (and thus fail to boot),
it seems preferable to have the proven old kernel and initrd.