I'm a big believer in using express passes at Halloween Horror Nights at Universal Studios Florida each year. Having a pass virtually ensures that you'll get through all eight haunted houses, even on crowded nights. The express line is always shorter than standby, and usually you only wait a few minutes, although express waits can get up to 20 minutes, or even more, on the busiest nights. However, that's nothing compared to a 90 minute or longer standby wait.
I go to the event almost every day, and every time I'm there I see people using their express passes ineffectively. They're a pricey option to add to your ticket, so here are two tips to make sure you get your money's worth.
1) Use a smart touring plan rather than relying completely on your express pass. Check out this article for my touring plan that almost guarantees you'll get through three to four haunted houses with little to no wait. Basically, it involves getting to the park as early as possible and doing The Walking Dead and La Llorona rather than the sound stage houses first, then hitting Havoc, then going to the sound stages (doing Afterlife before the sound stages is optional).
If you follow that plan, you save your precious express access. That way, if you're staying until closing time, you can redo the houses that you did early through the standby lines.
2) Do not use your express pass if the standby wait is 15 minutes or less. Every week I'm one of the first people through The Walking Dead and La Llorona. Because it's early, the wait is negligible. However, I still see people proudly using their express passes to pass maybe a dozen people in the standby line. I snicker to myself because that's one less party who will be in front of me in the express line when I repeat the house later.
It's fine to use up your express access early if you're only planning to stay for a couple of hours. If you're making a night of it, it's much smarter to do the standby lines while they're still short, then use express at your leisure later.
You don't necessarily need express to enjoy Halloween Horror Nights, but it makes things go much more smoothly on busy nights. Use my two tips and you'll get the biggest bang for your buck.