You really should try the log spikes. I first started comparing and working with them to spikes in A-9.3 and they are much better. The regular wood spikes are faster cheaper and quicker to deploy but they take damage when something hits them. They degrade quickly.
The log spikes are only damaged if you hit them but keep damaging as long as the thing being damaged is in range.
Ideally, you will want to dig a trench at least two spaces wide all-the-way around your fort. Then place the log spikes in the trench two spaces wide, same as the trench. This will insure maximum damage to your enemy's as they attack the fort because of them having to walk on them.
Zombies will attack the spikes but not so much and log spikes will last so much longer than the other type.
Plus you can upgrade them. If you have the metal, you can make medal log spikes which can save wood but cost a trainload in medal. They are better both in defense and offence but expensive.