I have got several sensative Strips FW 0.8.
With previous Smarthome-System I could set their wakeup time on 7 Days.
With PaperUi some shown as maximum 1 Day, other could be set to 604800 (7 Days).
With Habmin I could configure all to 604800, but the Values are not been set. Maybe because nightly heal gets previous Values, before new are send?
In this case heal should be wait until new values are accepted automatically.
Try manually waking up the device after you set the new wake up interval. That should cause the new wake-up interval to be sent to the device.
I know, buts that’s terrible work. 
Could be a good option to have more variations with heal network.
First: never heal devices options pending.
Second: something like heal two times (and then stop healing) could be great, because if you have got a stable Mesh, all working heal is not needed anymore, or is there a mistake in my thoughts?