The typical beer runs between 2.2 and 2.8 volumes of co2. There are exceptions- Belgian beers are generally higher while American stouts are generally lower. The general rule of thumb would be 14 psi with 5ft line to have a balanced system. Yes there are times when longer/shorter lines would be ideal along with different pressures but unless you plan to change this with every beer you put on draft then the above is the most proven method. Also location matters ie. if you are located closer to sea level or in Denver. I like to use 12psi as most of my beers have a little less volumes of co2 and keep 5ft of micromatic 3/16 vinyl line.