AX2009 - FA set up

as far as I can see, there is only one FA posting profile can be selected under the General Ledger parameter page. Is it a common practice for the user to change the value of the FA posting profile in GL, even after the FA and GL process have been set up and transactions being generated ?

If not, can I say each company will normally has ONE FA posting profile set up ? but detail setting in that FA posting profile can be changed further down the line ?