With any event tapers are important. For a half marathon you’re probably looking at roughly two weeks. It just goes back to the fundamentals that you want to absorb your training, rest and recover.
There’s no point in putting your biggest training week just before your half marathon because you won’t get the benefit, and you will run the risk of injury, illness, and fatigue.
Not everyone likes to taper, because often people think they’re losing fitness, but it’s almost like you’ve got to recharge the batteries. You want that itchy feeling where you just want to get out there on race day.