I have cash, and I keep it forever. I am slow to spend cash. If I go to the grocery store with $70, then I carefully spend less than $70.
If I use credit or debit, I'm more likely to spend more. (I get around this with a list, or just by not shopping.)
I suppose that's a natural limit on it, but also don't see the point. If I need milk, bananas and eggs for the week, but I don't have enough cash on me to buy it all then what have I gained? I go hungry because I didn't carry enough cash? Yes I guess I'd spend less, but I don't see much value in that, I'm not that poor. I buy what I need, how I pay for it doesn't much affect what I decide I need.
On the other hand I never get soda or vending machine snacks. And never feel much need to.
Personally, I did best on my grocery budget when I used a cash only system. I still do pretty well.
For example, it's not just "oh I need bananas, eggs, and milk". I have food in the pantry, fridge, and freezer.
So let's say that my budget is $70, and I need things that add up to $90.
I don't buy all the things. I leave some things behind.
Of those things, which do I need the least? Milk would be hard to go without with the kids. Coffee - well, I could survive with work coffee and tea at home if necessary.
Eggs? I like eggs, we eat eggs, but I could skip them for a week. I could make bread instead of muffins.
Setting a budget and taking cash means I'm choosing to purchase SOME things that I need, just not ALL things that we are out of. It also means I'd have to be more creative in the kitchen. With cash, too - that $2.50 bag of chips doesn't look so great when we are almost out of milk.
It's very much a personality thing though.