^ Yeah I've helped out a few people that have done a lot of prerequisite fortifications for their Storm Shields but the biggest thing is it's all up to your playstyle. I've been with some others that have set up a bunch of traps or just grid like fences all the way to slow down the monsters. I've also encountered some that have a lot of defender placements around to help out. I recently traveled and unlocked the next region, Plankerton, and you start with a new location and Storm Shield. There were a few times when I couldn't build enough or defend against the hordes of zombie husks so I had to do the Storm Shield missions again and repair a bunch that got wrecked. It really depends on how many and who joins you on those I think.
Not related to that, yeah just unlocked Plankerton the other day and am doing missions in the 19+ zones. It's quite a challenge but I've got the weaponry to handle them thankfully. It just sucks that it always boils down to nuts and bolts (what resource you need to craft ammo). There's a bunch more you unlock and can customize. I've got a bunch of Hero XP which I decided to place evenly throughout my characters. I could have saved up and evolved one of them but those are also the decisions you have to make. There's a lot of RPG elements with this game, with some slight tower defense (esp if you build it out that way in some levels - like yesterday a stranger and I had a really good chokepoint kill zone going on with walled off sections/traps for the floor, wall and ceiling on the main kill zone) but ultimately yeah you're shooting things. The higher leveled monsters can turn the tide of the battle if you and your teammates don't respect their presence. Overall I'm still enamored with this game lol.