It depends on how you define "proficient". It also depends on the person.
I'm probably going to get told how unsafe I am, but that is often the number of hours I log in 2 years. I don't have any problem passing flight reviews or check rides, either ground or air portion.
Things that I feel help me are lurking in forums such as these, flying with an instructor if the conditions are outside my comfort parameters, and thinking things through during the flight.
Engine out 300 feet up on a climb? Get the nose down, get to best glide speed, make for the most open area possible or the least solid object. Fly until it stops.
Edit: I also tend to only fly planes with steam gauges, which are relatively consistent in their user interface, unlike the glass panel planes. I only fly VFR as well. Foreflight and a paper chart fills my electronic/ nav needs quite well. Keeping it simple helps as well; most Cessna 150s are simple planes.