"Efficiency" is highly overrated. If you are at 70% plus already, you are fine. You can spend time tweaking your process to get that up a little, but getting up to 80% is only going to save a couple bucks a batch. Obviously, it's nice to save those couple bucks, but it is a pretty small benefit. It's much more important to be consistent so you can can brew the beer you want every time. eg if you are consistently at 72%, just plug that into your software and you'll be golden.