At least in JFK Jr's case, it's likely he didn't fly regularly, and therefore took instructors with him in many cases when he was unsure. IMHO, he probably suffered more from disuse. Because he didn't fly regularly, had low time, and got into a situation where he needed those unused skills, a tragic event occurred. That's always been a motivator for me to go out when conditions are right to stay proficient. It may mean flying an extra leg or something, but chances to get a live approach or night landing are opportunities I try to grab hold of.
To the OP: I think you can safely branch out a little. I know you're trying to save some money for training and all, but I hope you will have some (safe) fun with your PPL. Becoming proficient in your plane in visual conditions provides a good foundation for instrument training. You'll feel comfortable with what the plane needs while maneuvering, and transition from IMC to VMC (especially for circling approaches) will be easier. Bottom line: Enjoy your new privileges, and try to balance saving money and being the PIC. It will pay off later on.