Let me say first of all that I believe it's possible for a person to over-plan their trips. I've never gone all the way RTW, but I have taken some pretty extensive overseas trips in my 68 yrs. Be somewhat practical - don't try to see everything in one trip. Be honest with yourself, and ask yourself why you want to go RTW. I often see people who travel so fast through one country that they remember little or nothing about that place. It can be extremely hard to pack for RTW when you're going from winter to summer on the same trip (I thoroughly believe in packing very light - one smaller backpack, 40L).
I just returned from Turkey and Rep. of Georgia, and I discovered a better/cheaper way to use accommodations - to rent shared apartments with Airbnb, as well as using smaller guesthouses.
Back to my first thought about not trying to do it all in one trip - maybe you should choose a theme for your trip based on your interests (photography, animal life, food, visiting developing nations), and mainly go to the areas that allow you to witness/participate in these areas of interest. My recent trip was a "food trip" and I took local food walking tours (in many areas, short cooking courses are available - especially SE Asia).