As I've said on here before, it took me 48 hours to get to my first (fixed-wing) solo. Reasons were probably a combination of a difficult airfield (Welshpool), mediocre instruction, and my own problems - lack of natural ability and loss of confidence at an early stage due to a personality clash with an instructor. At the time I beat myself up over it, as we all do. But within a few months it made no difference at all. And now, as an instructor, it positively helps - I KNOW what it's like to struggle, watch others passing you, and wonder if you can make it. I also know what to do about it.
These days, people come flying with me on trial lessons, and more than one has marvelled at what they perceive as my "completely natural" flying ability. Me, a natural? That's a joke...though I did take to helicopters a little more quickly than f/w. But I only look like I was born in an R22 because I have hundreds of hours flying them. And that's how you learn to fly, and go solo - by practising. And if you need a little more practice than some, who cares?
Recently, after a student brought back an aircraft with no fuel in it, another instructor commented to me that you can teach someone to fly, but you can't teach them common sense. A good pilot is one who is safe and makes sensible decisions. It has little to do with ability to manipulate the controls or how quickly you learned to do that.