When it comes to professional manicures there are no hard and fast rules as to how often you should have one done. It depends on your lifestyle and how important manicured nails are to you.
If you typically prefer medium to long nails which look perfect all the time then you will need to get a professional manicure once a week. If done properly, you should easy be able to get a full week between manicures.
Now if you are more active and find that short length nails are more practical then you can leave up to two weeks between professional manicures. The advantage to every two weeks is that you save money and since your nails are worn shorter you can easily do polish touch-ups yourself.
That said, the faster your nails grow and the more abuse they undergo, the more frequently you will need professional care.
I’ve also found a protective topcoat applied every two to three days is the key to maintaining my manicure between professional appointments.