Hours don't mean much. In fact, they don't mean squat. For example, a student whose school is an hour ferry from the practice area might have considerably more hours at solo time than one at an uncontrolled field with everything nearby. A student who can only fly once every two months is going to take a lot longer. A student with multiple instructors (not unusual in the rush to grab the big brass ring, for instructors to flush through a school like sludge in a pipe) will take longer. A school which sets a minimum time for the student, will cause the student to take longer. Some training aircraft will take longer. Switching types of training aircraft, may prolong the process. Life happens, and family emergencies, funding, work, scheduling, maintenance, weather, or any number of other things might intervene to delay training and delays tend to cause repeat training. One step forward, one or two back. When I did my solo, I was in high school and bicycling 30 miles each way to the airport, and solo was a year in the making. Private another year.

If I were to receive a student who told me he was ready to solo, I wouldn't simply sign him off and send him into the air. I'd evaluate him myself, apply any training I deemed appropriate, and by mutual agreement, solo him. A student who has several instructors might repeat this process.

It's not really appropriate, without having flown with a student and with scant detail, to make a determination that the student isn't fit to fly, based on the number of hours he might have. I've had students who soloed quickly and hammered out their certification in the minimum 40 hours; my first student was done in 40.5 hours, passed with flying colors. Others took longer, or wanted more time. I never pushed anyone, nor insisted that they meet an hour-based deadline. I've even had students who held pilot certification, but who didn't feel comfortable doing this or that, who insisted that an instructor go with them all the time. I had no issue with that. A safe call on their part. Some might say overly conservative, but they were fine, and knew their limitations and drew a line well inside of them. Personal choice.

I have had students who seemed to not get it, who struggled, and in a couple of cases, I determined that I couldn't move them any further toward their goal. I asked another instructor to fly with them, and they progressed. The student continued and did well with that instructor. Because teaching is all about the student, placing the students interests first and foremost should be the norm, but it isn't always the case. If a student hasn't soloed by 50 hours, I'd be interested in meeting them, flying with them, and seeing what needed doing; it's true that not everyone is cut out for flying, but in several decades, I think there have been few enough I could describe that way that I could count them on one hand. One student had 100+ hours; he was in his seventies, and he wasn't progressing, but he didn't want to stop, and so long as he wanted to keep going up, and so long as he understood our assessment, I had no problem continuing. He understood he wasn't going to solo or certify, but he enjoyed the flying, and that was fine. I wouldn't be too quick to judge a student based on hours; I'd much rather fly with that student, spend time talking with that student, and make a determination that way. Hours don't mean squat.