Every part of the home has a shelf life.

However if I do a BRRRR I can achieve infinite return by extracting all of my investment.

You just need a purchase agreement between the two of you with clear terms that either an attorney can draft or you may be able to find an off the shelf generic one (I never recommend these as they are too generic and don't protect either party), or you can ask a broker to prepare one for a flat fee.  

I have a few units that are bringing in some cashflow, but I was able to BRRR them for infinite returns.

Most of them have a 2-5 year shelf life. 

To believe in infinite appreciation or a almighty supreme being you must have faith because there is no proof.

Money tends to be infinite but individual time is not.

Usually this time of the years things slow down and inventory isn't flying off the shelf if you know what I mean, but for two different clients I wrote two offers at asking price close in a week cash offers and they passed them up!?

There is no cash flow for 3-4 years as it is built, but then after a return of capital in years 5-6 you will have an infinite return for your cash on cash and be able to reinvest that money, but more importantly, the property will be held for approximately 25 years so your wealth will grow possibly 30X over that period of time.Or, ideally, do both!

There is an infinite amount of ways to get and attain deals.