One LLC or multiple for managing properties ?

I'm a relatively new investor with three SFR's, looking to buy #4. I've been advised by my CPA to create a separate LLC for each property, along with individual business accounts for each. From what I understand the LLC's provide some protection from my other assets and there are tax benefits associated with them. The initial setup cost about $300-400 for each which I thought was reasonable because they are being filed in a different state than I live in. However each year he's preparing my tax return the filing cost for each LLC seems to be going up, from around $350 to $480 for each LLC, not including my personal taxes. Is there a more cost efficient way to manage my properties, such as perhaps one LLC to cover all properties and a large umbrella insurance for liability issues ? Any guidance would be greatly appreciated.