I disagree with this answer. Quality Differentiated lesson planning always takes more time. Time isalso spent with organizing supplies, materials, and structure. It is engaging and rewarding work, but it takes time.
As I stated in another question, when ever you create more than one way to do something it takes more time. It is worth more time because the learning is genuine to the learner. The learner may acquire the information more rapidly so in that way it may take less time over all.
How does it not take more planning? If you have the same structure for every single day of class you are not using differentiated instruction and if you do use it, you use different lesson plans and incorporate different activities, so how does it not take more planning?