Most of what they recommend only makes sense from an operational standpoint if you are a larger investor and have a team to help you manage everything.Also, ensure your REI-savvy tax pro and your REI-savvy attorney link up during the entity structure creation process so things are optimal on all sides.Just something to keep in mind as you're beginning this journey.Answering your question, you'll want a checking account (minimum) per subsidiary entity and for your parent entity.

However, you can choose to do a Cost Segregation Study and instead of depreciating the property as a whole you depreciate each piece of the property some of which have a shorter lifespan and that allows you LARGER deductions sooner!

The only thing in our agreement about marking up bills is that they may add a surcharge on larger projects (several thousand dollars) as a coordination fee.

For larger properties, some of our clients run another cost segregation study at the time of sale.2) Partial Dispositions - Taxpayers can carve out and dispose of components removed or demolished from a building.

If not they may require larger lots to separate wells from sewer septic system. 

My assumption has been DSCR is the main driver, coming from my institutional experience (larger deals) we usually target a 1.2 and over DSCR.

Duplexes are worth quite a bit more per sqft than Fourplexes as there is a larger buyer pool and it opens to the non-investor customer.

Banks ask for larger down payments to shift risk to the buyer/borrower in default. 

Building a network, finding mentorship, joining local REI groups, and expanding your portfolio through larger investments can help.

A bit of clarification on the larger property: "That large property also makes the same as the smaller 8-10 properties as well"Are you saying it makes as much as the the 8-10 smaller ones, or as much as the the 8-10 smaller ones combine.