If one goes bankrupt, it may take all the others with it.You may not need an LLC for each individual property, but each LLC you do have should have its own bank account and books, and should behave as its own completely separate entity.

In fact, if this is your situation, you might want to even create 3 LLCs to separate the assets from each other.  

I do recommend a separate checking account for all business related items as well it will make doing your accounting far easier!

As for the others, you need to keep things separate.

I recently did a hard money loan and a refi (separate transactions) with the same lender and my closing costs seemed really high.  

Just as important to the financial/legal structure is the emotional structure you put in place and few think of this part upfront.  

My Real Estate partner from 30 years ago, owns 90 separate Trailers on their own lots.

AirBnB has grown radically over the past few years and these emotional bidding wars for cabins by people with zero REI experience are appreciating the prices vastly higher than the admittedly high inflation rate. 

On a separate note, looking to network with other real estate investors in the Charleston area!

Separate question.