As you already said, there's ALWAYS another sale. One holiday sale isn't going to give you more of a discount than another holiday sale. A lot also depends on supply and demand. If things are slow, the discounts will be greater. Also, if one appliance model isn't selling well, the discounts on that one will be greater. Or if it's about to be discontinued, you can get a better deal. Those factors influence the price more than which holiday it is.

There's a DW I am interested in (for a friend), and every time I check its price on the AJMadison website, the price is changing, kinda like the stock market. Up $40 one week, down $20 the next, up $15 the next, and so on. For the really best deal, I think you do best by talking with your salesperson, or if buying online, calling them, and saying "can you do any better on X appliance?". They often will.

What you don't want to get sucked into, is buying appliances too early for install, cause you think the sale is too fantastic to pass up. Most appliances have warranties that kick in upon delivery, not upon installation. If you buy an appliance, say, 4 months before you install it, you will be foregoing 4 months of warranty. And you'll have to store the appliance(s) somewhere if you aren't ready to install--and it is during storage that often things get damaged, by being jostled, pushed, dragged, having things dropped on them, etc.

I agree with akchicago on not being sucked into a sale. I bought a DW and walloven about 8 months ago because I thought the sale was great (30% off). My remodel is taking longer than I expected (yes, it is STILL in process). I ended up returning both appliances after 4 months and it was easy because I never let the store deliver them. Since they hadn't been delivered, it was no problem returning them - except for the good-natured heckling from the salesperson who I had to promise I would buy from again when I got around to it.
Anyway a couple of months after the return, the wall ovens were 40% off. Still didn't buy. Now the salesperson is telling me they will be 50% off next month. And the DW? Well, I just got a TOL KA for 40% off.
So my recommendation is wait until you are ready or near-ready. If you just can't pass up what seems like an unbeatable deal, check if the warranty will start on delivery date or sale date and if the former, see if the warehouse will hold it until you are ready for delivery.

BTW, forgot to mention that if you are ready to buy now, Sear-s is having a 30% off sale on their Energy*Star appliances and their KA DW are 40% off. That's where I got my KA DW.

Agree that there will always be another sale -- BUT, I did find the "doorbusters" at Sears during black friday to be the best discount by far. The only caveat is that there are very limited numbers of units available, and usually only 1 or 2 models. But if they happen to have the model you are looking for, or similar, the price can't be beat. We got our washer/dryer on black friday, and it was much much cheaper than any other sale. DH had to wake up at 4am to get there, and since they go in the basement, I didn't really care what color I got.

My French door LG fridge at Home Depot was cheaper 2 weeks before black friday than it was on black friday. There was an extra 10% off before thanksgiving.