I currently don't have the busiest schedule so I don't really plan too much. But when I did have a busier schedule I didn't plan as much as I should have. I'm trying to be better
Planning varies on what needs to be planned. Certain events in life needs longer time. As a rule I only spend 20-minutes planning basic daily/weekly tasks. Sometimes important aspects such as a piece of work that needs doing or planning a big life event this is going to take longer the more you plan the more successful it's going to be
15-30 minutes in the morning, including journaling to set my mindset for the day, aligning my daily tasks with my weekly goals, planning my to do list, and scheduling time for my events and tasks. I also spend an hour each Sunday planning my weekly goals (aligning them to my monthly goals), and handling all the chores to prepare for the week (planning food, finances, cleaning, etc. I subscribe to services for cleaning, laundry, and food so I arrange those each week).
Depends on what I’m planning for! My daily To Do lists typically don’t take longer than 10-15 mins as I’ve been doing them for several years. It’s easy to see what’s leftover from the day before when you’re consistent. If I have a big day ahead of me that requires being in a million places at once, I plan my day out by the minute; otherwise I know I’ll get sidetracked, & THAT takes a while.
For the day ahead (the night before it): about 5-10 mins tops. For the week ahead: maybe 15-20 mins tops. For the month ahead: it depends, but I could guess 30ish minutes and coming back to it as needed. Planning shouldn’t take longer than action, unless you’re setting up an action plan for a long-term project.