Proficiency, what an elusive word. You could go on forever attempting to describe proficiency and not cover all the bases. What you describe is take off, getting around the patch safely and under control and some sort of landing. Even with a cub style airplane you have so many options from a small foam UMX type model to a .40 to .60 or bigger trainer. You have to take into consideration the type/size of model, the field it's flown from, surrounding obstructions, number of other flyers in the air at the same time etc., etc.

The guy who flies by himself in his back 40 might hand launch and land in long wheat/hay etc. Proficient for his type of flying not so much for a club atmosphere.

The way I look at it is you need to take off, get around the patch safely and under control then land in a designated area with control. If you're flying in a club environment your fellow flyers must have sufficient trust in your abilities to operate safely and in control. Remember the learning curve will be different for everyone. It depends on many factors and one should not think of it as how fast can I fly on my own. Concentrate on learning to fly safely and under control at all times. Part of the goal is to have a fun day of flying and bringing home a model that doesn't need repairs. If you're joining a club they will probably have additional expectations and rules.

I can't tell you the times a new pilot will learn to fly inverted then attempt to do worm burner passes get in trouble and pull full up only to plant his model firmly in the ground. He wasn't ready for that type of flying, needed more practice at height and was not proficient enough to fly that manoeuvre. The only way to learn is to venture to the upper end of your comfort zone but do it at altitude, so you have a chance of recovery if things go wrong.

Another thing I see is a new pilot who just got their wings take off, bore holes in the sky then only considers setting up for a landing when he is running out of fuel and has to land. This all or nothing approach does not help to improve anything but your repair skill set. I will often spend most of my time practising landings and take-offs till I get them where I like them. I also practice recovering from upsets and engine outs from take off to at altitude. Watch how many lose and engine at height and either use up altitude and land short or stall/spin it in at the end of the runway or needlessly over fly the runway and land in the scrub at the other end of the runway.