Particularly in a four-plex, where you may need to replace several of the same items (lets say appliances) over the same time due to having multiple units.

This assumes everything is run perfectly w/ no vacancies, major capital items....  

It provides many strategies for managing your rental business and I found it quite helpful.As for your concern with large cap ex items such as roof replacement, HVAC etc, as long as you budget for those items and still cashflow, you should be ok? 

One other item; San Antonio has a website for looking up contractors' licenses; it is NOT 100% reliable, as demonstrated by a few followup calls I made.

A few items in the kitchen and bath...maybe something on the mantle...all tastefully done....it can be very effective. 

When the tenant moves in, we give them a Move In Packet, which includes "Move-Out Instructions" too, which has three pages: Move-Out Instructions, Minimum Charges for Services and Turnover Costs guide (typical charges for damaged items or need for additional cleaning), and Notice to Vacate form.2.

There are a number of items that make up that criteria, but there are two that stand out:1 - You must be really good at Analysis (market, rehab, and property)2 - You must build (and grow) your Buyers list. 

Plus, storage for such items can be problematic.

Not included in that are items like - Finding new leases when a unit becomes vacant- Repairs and maintenance etc4.

I'm sure along the way of learning the items above these answers will come about as well.Hope that helps.