We abandoned the Capital One Venture a few years ago. I build points pretty quickly with the other cards, but we do a lot of credit card spend each year for our chimney cleaning business, and we do own a lot of timeshares. And I do manufactured spend, too, while it works.
I can easily see our manufactured spend process ending at some point. The credit card company could stop 5X points for office supplies (or just drop us from the credit card for maxing out that benefit), Staples could stop selling Visa Gift Cards, our local store could stop selling MO's. There are other things, too, that could stop our procedure (the bank could stop taking MO's). It's a fragile system. One step depends upon the rest of the steps, and it's not easy to do, either.
With our Manufactured Spend and timeshares, and travel expenses, restaurants, groceries, utilities, and everything else we charge, we easily spend $250K on our credit cards each year. $100K of that is MS. That's 500K points per year.
It works now, but it could all end at any time. I posted earlier in this thread what UR points have done for us in our travels to/from Hawaii, and a Southwest ticket of $100 is only about 6,000 points. 100,000 points is a lot of Southwest flights. 100,000 points transferred to Hyatt will get us a lot of nights in San Francisco, that's for sure.
It's difficult to compare credit cards one to another, which is why I have a spreadsheet. It's kept me sane because I can have a column explaining the value of points with each card, so I can refresh my memory when I wonder what card to use for a purchase.