Really the only reason is that once purchased, the number of points in a contract cannot be changed. This really only comes into play if you want or need to sell all or part of it in the future, or will it to someone else. Even if you never plan to, you never can be sure right?...
Large point contracts, say over 160 points, command a lower per point resale value. Larger contracts are also more difficult to find a buyer for. You have probably seen this while looking at resale listings. Larger contracts have a lower $ per point asking price. This is simply due to the fact that the larger the contract, the smaller the market of potential buyers due to high overall cost. The other is the fact that larger contracts are less desireable (reasons I am currently explaining).
Other beneifts include the ability to sell some of your ownership if your needs or financial situation changes. If you own 3 x 100 point contracts, you could sell one of two of them. With a single 300 point contract, it is an all or nothing deal.
The same goes for passing the deeds onto children. A single contract is more difficult to distribute than several smaller ones.
Whether or not you want multiple contracts at the same resort or at different resorts depends entirely on your needs and preferences. 3 contracts at the same resort is functionally the same as one large one (same Use Year -add ons). Contracts at separate resorts would give you home resort advantages at more places, but with a lower amount of points at each one.
Bottom line. As the owner, you are in a much better position holding 3, 100 point contracts than a single 300 point contract. Not only are the threy more valuable combined in terms of market value, they are also easier to sell, and can be sold or willed separately. In the current market, many 25, 50, 75 point contracts sell before they can even be listed there is such a high demand. This makes them almost a liquid assest (an exaggeration, yes).
and Yes, I would definately want all contracts to be of the same Use year, aka: "Add ons".
This intigues me. Tell me why. Should the smaller contracts be at the same resort, same use year? I know we have 3 contracts but that is b/c we added on twice. What are the benefits. Thanks so much for this input.