High PD kinda useless.

[Foodstamp]

Some nations seem to get better returns for PD as well. I noticed that EA Arco PD is VERY effective.

[Caduceus]

I don't have much experience, but I have had good experience with the Arco PD.

[Ballbarian]

In Dom2, I set just about every province to 11 defense. In Dom3 I have found 21 to be reasonable. Like Gandalf, I too compliment trouble spots with a local commander or two. In strategic choke points (if the gold is available) I crank it up to 30+, but that is rare and usually pretty late in the game.

[Stryke11]

High PD for MA Ulm has never let me down. Although in my current Pythium game Mictlan of all nations routinely rolls my PD of 60+ and Oceania too. Makes me wonder if the money spent is worth it. I think out of maybe 15 attacks per turn to provinces undefended except for PD around 60, 2-3 are successful.

[KissBlade]

you should only build pd's at choke points and even then it's best to pad it up with one or two battle mages. I use pd often as chaff and anti call of the wind forces, nothing more.