When we buy a note, we get interest and principal throughout the term so that principal diminishes over time.

It appears that recommendations from both @Richard F. and @Shawn Holsapple have disappeared due to diminishing quality?

Yield diminishes as we approach maturity in some circumstances however "cash flow" on a fixed rate loan actually remains the same.  

When you factor in the interest rate + monthly expenses, the ROI can quickly diminish.

I guess Dan Kennedy's quote lit a fire under my butt when he said, "Hanging around poor people who place very little value on time-theirs, others', or passing time in general - your own productivity will diminish.

Return on Equity = Cash Flow after Tax / Current Equity in Property As appreciation outgrows your Cash Flow, ROE diminishes and it may be time to sell or refi in order to buy more property and have money work harder.

Also I would suggest checking if your bank or credit cards are offering a balance transfer at a lower rate so you can diminish some of the higher interest accounts.

It really is increasing cost's and complexity not diminishing them. 

It's always possible to over improve into diminishing returns.

The key is to rehab to the point where it looks really nice but you didn’t overspend/ When you overspend don a really nice rehab, there comes a point where your ROI starts to diminish because not much more will push the price up.