We must do an analysis with data not personal bias.
A barracks has 1500 hp and takes 30 seconds but a 15 wooden palisade takes 12 seconds and has the same amount of hp (1500)
A keep has 5000 hp and takes 180 seconds but a 45 stone palisade takes 60 seconds and has 2x3500, totaling 7000 hp
There is the problem, please developers balance both the Hp and the time to produce walls and palisades