I am a fan of two separate house banks on a crusing boat. One of the big advantages is you can run separate battery ages and even chemistries. When the batteries are identical you can join the two banks together with a flick of a switch.
I have run batteries of different ages like this on two banks for several years without any problems.
Pukets equation does not have much impact unless you have very high demand devices.
The subtleties of managing two banks are a bit involved, but if follow two simple rules you will get good results in practice.
1.Join the banks together when charging
2 separate them when discharging.
When discharging try and run the batteries to similar soc. Good instrumentation helps, but roughly even is fine. In practice this will mean something like switch the banks over when you go to bed
One of the advantages of batteries of different ages is they are unlikely to all fail at once,this can be helpful when crusing remote
locations where batteries are difficult to get. Unlike other boat parts
it is often not possible to ship them and battery life is always unpredictable.