I use protein supplements when I don’t have time to make a solid post exercise meal for my protein source. This is when I realize that I didn’t premake my post workout meal, which is about a third of the time. And I will use powders to bring a meal up to the protein level I want if the whole food source is low in protein (just to make life easier sometimes).
But you should be planning out your meals and knowing all the components ahead of time as much as you can. This isn’t an absolute must for all meals. But if you aren’t planning at least half of your meals, you are really slacking on your program. It isn’t all that hard or time consuming. You just need to get started and eventually it will be automatic most of the time.
Use the shakes as a quick fix, not as a staple.