I'm a buy/hold investor and during the last bubble, I sat out with the exception of selling off a rehab property (and stashed my cash).

If the author stashes the cash in a CD earning an inflation-adjusted 0% each year, then the reserves will be exhausted at some point well before year 30, which is fine because cash flow from the properties is meant to supplement the reserves in the long-run.

You're good.My vinyl siding houses always have some extra stashed somewhere.  

The conservative way is to stash those funds into a separate bank account but invest it somewhere else if you can get a small return but can keep it liquid enough.

He just needs a place" for a little while" until he "gets back on his feet."1 week later the cops are breaking down the door to seize his stash. 

As much as anything, I view this as a place to stash cash instead of putting even more in the stock market.  

To bugs, and critters, drug dealers who when they moved, dismantle the stairway leading up to the bedrooms, because the stairs is where they stashed  their stuff. 

I couldn’t have done it without having some “mad money” stashed away in our Roths.

Hopefully you'll be stashing away 20% in addition to paying the PITI ?

You'd want to account for that and hopefully plan in advance by having some funds stashed during the cash flowing months to keep the bills paid during your high vacancy times.As stated, vacancy loss is a negative line item under revenues so you can see how much potential rent was lost during any period.