Undercover and a couple of other sites do offer some discounts. I always peek right before I renew my AP and buy a ticket at a discount and then have it applied to my account before I renew. The 8 day is generally about 60-70 bucks cheaper through places like UCT and then you get full gate price credit when you apply it for upgrade or renewal.
Last Minute Travel Club is another place. I have used this twice and I plan to get my 2019 tickets there. I go to Disneyland California and each time I have saved approx $50 compared to Disney website
If you sign up for the Mousesavers newsletter on www.mousesavers.com they will send you a link to even better Undercover Tourist discounts thought their newsletter. The newsletter comes out the 15th of each month. It is a little bit better than just going through the Undercover Tourist website. Just order tickets today and they had an extra $5 off. It wound up being about a 10% discount.
If you or a person going with you is active duty or retired military, you can purchase reduced price tickets at military base travel centers or at The Shades of Green Resort. A five day park hopper ticket in 2018 was $246.
I used Undercover tourist for a 4 day ticket (got about 10 % off). will use this ticket to upgrade to an AP when we get there in March and will pay the balance with Target gift cards.
We bought 5 day hoppers from UT at a $68 savings over Disney gate price and will upgrade to Gold AP upon arrival Sunday. We'll be paying the difference with Disney gift cards bought at Kroger to gain fuel points.
Folks have answered to show there are but where you are right is for short stays
There are no discounts for 1 and I believe 2 day tickets. 3 and up are discounted in many places