b) Agree. Also, if possible, build the "city walls" great work in your capital county for further boosts to levies.
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a) Disagree
I agree with
@jhhowell - it's probably best to have a strong capital duchy (with multiple castles in the capital) and leave some space in your demesne limit for a few scattered counties. Holding the entire capital duchy is worthwhile because of the bonuses, and I think it's better to stack those bonuses as high as possible so you can use the rest of your demesne limit for other purposes. For example:
- if you want to keep vassals away from a border so they can't go to war
- if you want to hold lots of SR trade posts for the phat loot
- if you need to convert a county from tribe to castle
- if you need to wait for a few years before giving a county to someone (eg. so you can invite them to your court to break a disadvantageous betrothal)
- if you want to use the county to help you convert religion in the future (eg. if the county religion is rare, or if the county has a holy site - and especially if it has multiple holy sites!)
If you mean what he said here
Be aware that if you hold a county outside your capital duchy, that duke will have an opinion penalty with you because he wants all his de jure territory under him. Holding multiple counties in the same non-capital duchy is generally a bad idea, unless you hold that duchy title personally.
Seems there is a confusion.
Under normal Feudal conditions. (no tribals etc)
a) You can hold all counties, where your capital county is on de-jure Duchy without having created the title of the Duchy
b) Same applies on the second de-jure duchy you hold the rest of the 4 counties. Just don't create the title of the Duchy.
c) That way you have a demesne of 12 wide (or more) and still hold 2 duchy titles directly that aren't any of the ones in your demesne
MR aren't effected at all. Nor Dukes where you hold counties under them as this doesn't apply on this scenario as the duchy doesn't exist.
And if it does exist you are the Duke so no penalties from the counts.
If you want to keep religion of a county that belongs to a duchy hence you keep it yourself away from Duke's hands then so be it.
You have the option to destroy that duchy title. So no dukes and give the other counts as vassals to a duke of another duchy. That is why on new conquest to control all the counties of the Duchy and give to the Duke ONLY the 1 county/duchy and transfer the rest as vassalage one by one as you appoint counts. That way the Duke will never put a claim on them trying to consolidate. (you much not select the checkbox when you assign the duke).
That is why also is best to destroy the Duchy title when you claim a new territory and control counties & duchy and pass the counties as vassals to some super dukes viceroys. Saves a lot of hassle.
That is also the easiest method to build an Empire. eg from Asturias to Leon to Hispania without having to move titles and people around all the time and have a secure succession election constantly until you hit max Demesne, Viceroys etc.
Hence my rule of thumb is NEVER create titles if you do not truly need them and destroy them as soon as you do not need them. Penalties be damned. Just some carousing and forced rebellions will resolve the issues.