I do this too - I plan dinners and lunches, eg if having rice for tea, ensure I keep some aside for tomorrow's lunch and just add in some veg etc.

I write mine up with what I need to prepare for the next night or lunch now (eg marinate meat) or get out of the freezer. I do a fortnightly meal plan, and only cook half of each week (fridays are takeout and I don't cook) - I cook double of things like curries, pasta sauces etc so I just need to reheat those. Salads I make for the week during summer. My g/f also has a pile of insulated cups and makes up smoothies for 2-3 days in advance. My DH has also made his sangas (ham & cheese) on the weekend & frozen for the week ahead for years.