Training with and without a gi will offer different options. It will also keep you from relying on one or the other. Training without a gi can be faster. It can also be hard to be submitted in no gi as you can slip out of things easier. This can in turn make your submission much tighter and stronger. Training with a GI can slow things down and offer a different pace. It can be easier to submit someone since they can’t tear out of things as easy. This will in term give you much better defense as you have to be more aware and preventative.