That training guide looks like a good one, but I would probably need a custom training schedule because I've got a Spartan Beast and a Tough Mudder in that time frame. I'd need to design something to work around the other events I've got on my schedule.
Thanks for your answers everyone, it seems like the best course of action is to work up to 14 miles and 25-30 miles per week, but also resist the urge to overtrain.
I tend to set my goals incrementally, like currently my goal for 5Ks is 24 minutes, when I hit that it will go down to 23 minutes, when I hit that it will go down to 22 minutes, etc. But I think I've also hit the point where I'll have to work harder for gains.
My best 5K time in February: 27:45
In April: 26:10
In May: 24:45
Yesterday: 24:30