Is this just me, or have others had to deal with gradually escalating needs for mess? Over the years (decades, now) that my wife and I have got messy together I've fairly consistently found that once we do something, the next thing has to be "more" in order to be as exciting. Whether that's more mess, more extreme substances, or more outlandish situations, once we've done something together that particular thing no longer seems so appealing.

I wonder if it's to do with the "forbidden" nature of getting messy - once we've done something then that thing is clearly not "forbidden" any more, so I need to find something else that is. So far my twisted mind seems to have continued to come up with "more" but I find myself wondering - might I reach some "WAM ceiling" and find the whole thing loses its appeal? Am I alone in this, or have others had similar thoughts - and perhaps found ways of dealing with this need for "WAM inflation"?!

Understand what you mean. Also been wamming with my wife for decades. I've quickly reached a plateau in the complexity of our sessions. Since each sessions are couple weeks appart I spend a lot of that in between time fantasizing and planning that next session. I vary with 2 types of inflatable pool.. our bathtub.. our hot tub.. shower.. outdoor mud.. trips for tidal mud.. changing mess from water, slime and mud.. always a different outfit.. so even if the complexity of the session has reach a high point, I never get board and I'm always looking for that next session with my wife. She's not a wammer but she's been a great partner in my craziness Keep having fun.

I think you've touched on it in your post, because it sounds like something I've seen happen to people before, where their fetish escalates until it just blows, and they completely lose interest.

I guess rather than always using more, do things that are more creative with less, as a challenge?

I usually calculate you need 12 x 1kg cartons of custard to fully cover one fully clothed long-haired person in mess, including some clothes filling and a full messy shampoo. But, if instead of just pouring it on, you carefully spread and smear it, the result can be both more tactile, and equally messy, from half the quantity. Would something like that help?

At some point, I was there too.
1Kg of Nutella, 3Kg, 5, 20. The top was 120 Kg of chocolate spread.

I'm not sure if I just reached my limit. Or maybe I'm getting old.
But today 1Kg is more than enough. On rear occasions, I will use the big tube of Nutella of 3Kg.

I keep it interesting by trying new stuff and scenarios, but it seems that the amount is not the main thing anymore.

YES YES AND YES!

what I did? Is I started doing little messes. Like ONE banana creme pie.. seeing how messy I could get in it.
Or one big jar of mayo. One can of cheese
I have done quite a few of them I'm just hanging ontomy own little messes.
I would have the fun of it be? How messy can I get with this? Or "what can I create out of what I have here im not using?"
And that brought me a lot of fun and joy! Try it sometime! Like? Just grab a few things from your cabinet. Or buy ONE CAKE and maybe a little tub of extra frosting and see how far it goes!
That helped me kinda take a step back and realize.. I can have just as much fun in this one substance I created in my kitchenenough to fill like a gallon jug
I would pick out outfits that I liked too.
And just keep on picking it up and smearing and having TRUE DELIGHT with it!
I think you will find that it makes the bigger messes? Even more fun. And you are hella more grateful for them!
And? It's just fun to see how far it goes! I'm tellling you I made a whole body mess out of one banana creme pie! That was really fun!
A little can go a long way! Add some outfits or toys you enjoy if that's your thing for a while and then? Getting the big messes are a lot more exciting!
I hope this helps!
I would film them too so I could watch the mess I was making! The rinse off was really fun too! I'm finding a lot of fun in rinse offs lately! Keeping the tub plugged and seeing what comes with the water added to it.
Good luck!

This is my thinking too. It's easy to burn yourself out on something if you do it too often. Take a 10+ year break from sex though, and the simplest of things can make you want to blow. But try and divert from quantity. What you're really craving is novelty, and that can be achieved a variety of ways without eventually spending $12000 to fill a hot tube with orbees like a jack ass youtuber and then destroy your entire sewage system. But I digress.

Incorporate something new. Variety is the spice of life, as they say.

Pour a smidgen of pudding in your undies and go about your day.

Try something completely not related to WAM for awhile and then come back to it. It WILL be more intense.