Second proposal: Manually select which buildings to upgrade.
I may station men-at-arms in a barony where 3/5 holdings upgrade them while the last 2/3 are only for tax income.
At this point, I may not want to upgrade the tax income. However, I also do not repeatedly want to go back to manually upgrading the warrior lodges from level 1 to level 2 to level 3 for every barony I hold. Allowing me to tick [X] per specific holding (not just for baronies/counties in general) would be a great suggestion.
Upgrade Warrior Lodge whenever available [X]
Upgrade Blacksmith whenever available [X]
Upgrade Windmill whenever available [ ]
Like this. Especially important late game if I switch capital-realm and have to manually upgrade 6-tiers of levels for 10 different baronies.