The first three certainly seem to follow an arc.
A sudden outbreak where the recently dead rise again and look quite fresh, the living still outnumber the undead and the local 'militia' in the locality of the farmhouse eventually get that area cleared but chaos is described in the cities.
People refuse to destroy corpses and the emergency broadcast system (seen in the first film) is inaccurate and sending people into danger zones.
The characters of the second film fly over redneck militias like those in the first film who make sport of shooting the undead but pockets between the cities go missed (like the petrol station). The Mall draws zombies from all around. The zombies seem a bit more decayed and the numbers are definitely on the rise.
In Day Of The Dead the undead are much more decayed and out number the living, there is no visible government and what military does exist is are cut off and is reluctantly following orders given a long time ago.
If Land Of The Dead does fit in it could be between Dawn and Day but to be honest it feels out of place (it certainly feels more like an eighties film than Day does).
Diary Of The Dead in my view can not be made to fit in with the first three films or the fourth.
I haven't seen Survival Of The Dead so I can't comment on it.