My oldest was never in size 5 diapers (I can't imagine stocking up on 5 & 6 size diapers not knowing if they would ever be used) - he was in 4's until he was potty trained at 3 -3 1/2. I only bought pull-ups a few times before he was fully trained - he's only had 2 accidents at night.
My 2YO is in 3's, and not sure he will ever outgrow them. LOL! His 3 month old sister will probably pass him. She could fit in 3's.
I bought 2 big boxes of Pampers size 3 at Walgreen's when they had the Jane BOGO sale and I got a bunch of overage...so they were free. Their boxes were on sale for $17.99 I think.
I hate thinking my Pampers Q's will go unused. I don't really like Huggies. I think they are smaller than the Pampers - overall for size 2, I prefer the Swaddlers.
I guess if you want free diapers, we will just have to suck it up and spend some of our excessive ECB stash. :-)