Hmm, my dog has gotten better as she's gotten older, because I've gotten better as a dog trainer and part of the training includes rewarding her for offering stuff or trying new things to learn the task, and dealing with frustration (for both of us).
Some dogs - it might take a lot more repetitions to learn the new task - but then their reliability on performing new task on first command - is much higher ie 50 reps to learn new task; does it on first command 99%... and that 1% will be some massive distraction like just stepped in dog poo.
My dog - it depends. Mostly - has new task in 5 to 10 reps, but... reliability erm... then she will offer up the new trick when she wants something. So she definitely knows it's worth something. And that's down to my poor training technique. Must not reward unless cue'd... no matter how cute she is.