The last time I made lasagna, I made 5 of them - one we baked and ate that night (and as leftovers over the next few days), and the others we wrapped and froze. This requires you to have several Pyrex baking pans (currently 10-15 US$ each), and substantial freezer space (both of which we already had), but the work required for making 5 pans was perhaps 2x making a single pan, and if we are hungry and don't want to cook we can just take a pan out and bake it, dinner in 30 minutes with no effort. Baked and refrigerated they last several days, enough to eat over several lunches and dinners. Enchiladas also work well for this. Both make a nice alternative to the classic frozen stews, soups, and chilis.
I'm not so certain about that. I've seen a number of cases where people working on classic 'enterprise' systems struggled for a long time trying to solve problems that could have been neatly resolved using something that is considered 'theory' (like a dynamic programming solution, Lamport's vector clocks, or A* search) and after much trial and error ended up coming up with a ad hoc approach that mostly didn't blow up. If it's purely a web frontend to a database, sure, there isn't that much algorithmic complexity (that hasn't been implemented for you already), but usually there is more to it than that, and having the ability to look at a specific problem and say "You know what this is really an instance of (some already solved problem)" can be very valuable in programming (as in any other field of endeavor).