I find a combo of planning with ads and being able to adapt works best for me.
I have a list of no-fail meals that I always have ingredients on hand for–things everyone in the family (or almost everyone) likes. I buy those staples when they are on sale and keep my pantry stocked. I also tend to stick with general themes for the days so it’s not totally from the atmosphere. For example, Monday is leftover/refrigerator clean out day, Tuesday is new recipe day (more before I had several small kids, but now every other week or so?), Thursday is Pasta and breadsticks night…
I also have master list of meal plans with special circumstances designated that I keep in a household management binder. Things like quick and easy menus (more convenience foods, frozen foods, and things like burritos that are quick and easy), guests for Shabbat (Sabbath), Chinese for Shabbat, dairy only, etc. Each of these has a shopping list that I have written up on the second page of the plan, so I can just grab it and go if I want. I often end up adjusting, but I don’t have to.
I try to keep things flexible in my meal plan. When I hit the store, I have both my menu list and my shopping list, and when I see something I want to get on a good deal, I either incorporate it into my menu and replace the other meal(s) or jot it down to include it next week (if it’s not perishable).
Another trick is I often make two or more of something when I’m cooking. Two baked ziti, two quiches, two kugels, two pans of chicken. Label and freeze one and you’ve got a meal prepped for you to add into a meal plan in a future week. I keep an inventory on my freezer and try to get things turned over every 6 months.
Last, I tend to collect things in my pantry and freezer, so I often do a “pantry challenge”–I try to use only what I’ve got, or what I’ve got with minor additions like fresh produce or dairy. This often happens before Passover, but sometimes I do it other times, too. It’s good for stretching your food budget sometimes, and gives you a chance to try some new recipes (if you search online, many recipe sites have places where you plug in what you have and it gives you recipes with those ingredient–very helpful!)
Good luck!
