I'm afraid I can't agree with point 3: I did take a couple of trips as P2 but, even though they were fun in their own way, they added little to my learning as I was "on the wrong side" i.e. in the right-hand seat which completely alienated me from learning anything.
Point 1 I can certainly confirm: we all have our limitations, financial not the least, but whatever lessons you can afford will be more effective if they are close in time. Better to have three in a weekend, and then nothing for a month. However, to get 3 lessons flown, one would have to book 5 or 6 most times of the year, given the unpredictable wx.
Most of all I wish to confirm point 4: my final "aha-erlebnis" come from an instructor I had never flown with before, and he only said what others had said before him, but he said it in the right words and at the right time. Sheer luck, I reckon, but the trick was done and that's what counts.