I get far better battery life on my Note8 by NOT closing every app.
After years of toying with phones, battery stats, etc., I've found that Android 8 and the Samsung battery features combined is actually EXCELLENT.
The worst thing you can do is to use a package disablers and start going crazy. You end up with a ton of issues that require extreme measures to get that 6 or 7 hours of screen time.
White backgrounds, GPS on high accuracy, no power saving, auto brightness, and just uninstalling the apps I don't use that Verizon put on my phone. No disabling of stuff and I get very few wakelocks.
If you close the apps all the time your system is either an old phone or you are preventing Android from accurately learning your battery usage.
If the battery ever does drain fast, just look at the battery usage in "Unmonitored Apps" to see what the issue is.
If it's wakelocks, chances are if you're near WiFi you have router issues that ping your phone rather than Android having a problem.
Check the DTIM settings and Beacon Intervals.