[OnePlus 6 ROMs, Kernels, Recoveries, & Other Devel] magnamentis:
4% overnight considering that means something between 7-9 hours is ok, try to use measurements that are comparable, i.e. x%/h or x%/xh etc.

else a proper assessment is difficult and/or guesswork. if above assumption is correct that makes it around 0.5%/h if the 4% were per hour that would be horrible of course ;) hope not.

as to why it could be preferable to disable doze, that's a very personal choice and depends a bit on our conventional battery management experience, understanding and skills.

the reason why i dislike doze is that i hate delayed notifications and despite all the commonly know tweaks to improve that, due to the fact that i'm using several devices, identically setup as far as hardware allows, i can very clearly see when notifications happen on each device and the only way that all my phones ring or ding at the exactly same time, within split seconds and not within sometimes minutes, is to disable doze.

the moment i receive a notification on one or two devices and wait in vain for the other devices to do the same, at times up to 5-10 minutes later, this drives me mad and makes me aware of reliability issues.

now if it were always the same devices that are late one could try to find a solution, but sometimes it's one and sometimes the other and some apps register success and won't notify on delayed devices at al because the app server things it has been delivered.

now as it happens, my phone (cell phone calling) main device is going loud in the morning 1 hour before the multimedia device and that means for example, that if the main phone is delayed and a message is notified on a secondary device that is still quite or on a spare device in the kitchen or in the office, i will miss that notification for quite some time, depending what i'm doing, could be sports could be taking a shower or having a chat with my kids.

only way to be sure that that notifications arrives on all devices at the same time without delay is to de-activate doze at all and it works.

now if someone has a bad battery life, let's say 1.5-2% per hour in idle, that won't be fixed by doze most probably, because that means something is not working correctly.

to find out what that is, one needs a very good, best rooted battery monitoring tool that provides a proper history and %/h and a mA/h usage statistic.

percent alone only tells percent form overall usage per app or overall but that is not useful because 100% can ba 5mA or 1000mA depending on the overall used juice. what we need to know for a proper troubleshooting is the absolute consumption per app, and not a relative consumption.

BTW i'm not using greenify or amplify anymore like i did a few years ago but i'm still using xposed.

in most cases there is one or two culprits that spoil the show battery wise. without misbehaving app one usually has quite decent battery life nowadays even without taking special steps to improve it.

what i can recommend and what certainly will make a huge difference is to control radios:

most people blindly use LTE as a stand, even though LTE without top coverage is a huge battery hog, even with good coverage it's consuming considerably more juice than 3G or 2G. so what i always do is to switch to 2G while display is off if no streaming app is active. further i keep as much as possible offline so that i don't have to permanently draw data for music or whatever else during idle.

but there are so many possibilities that it''s better to come back with an individual analysis before someone else is going to guess through them all ;)

if your battery life is bad in your opinion, provide a log of the kind described above and/or try to find the app(s) that use too much battery and start with clearing app data, resetting settings to default, uninstalling and re-installing the app and avoid restoring app data from TiBu or similar backups.

those are good apps but at times, i.e whatsapp and other apps get borked by using restoring form backups and SocialMediaApps are very often responsible for bad battery performance because once they're optimized they don't work properly and once they're not optimized they sometimes become battery hogs.