Hakeem
Hours at first solo is not in any way a good indicator of a pilots ability, basically because there are far too many other factors involved.
Just to give you a few thoughts from an instructor's perspective.
Ability of course is one factor, but really quite a minor one when compared to all the others combined.
Factors such as
currency (probably the single biggest benefit to any student pilot) have been mentioned already
Weather on the day - you're unlikely to be sent solo on a day with strong crosswinds, or even a gusty headwind, therefore may end up doing more dual circuits on these days to maintain currency. In the UK climate at certain times of the year, I have seen this add up to 5 hours for an otherwise 'ready' student
Airport environment - Most of my instructing was at a busy commercial airport, with students averaging maybe 4 landings per hour in the circuit, due to a wide circuit pattern and frequent holding as commercial traffic took priority. I know that at some small airfields (due to tighter circuit pattern, lack of commercial traffic and sometimes a lower circuit height), it's normal to do 10 or even more landings in an hour. In this sense 'Number of landings to first solo' would maybe be a better comparison than 'hours', but even then there are still too many other factors!
ATC Vs A/G Radio - On a similar theme to above, getting comfortable with full ATC at a commercial airport, ie switching betwen ATIS, Ground and Tower frequencies, and being safe to understand and comply with a large number of potential ATC instructions, will generally add a considerable workload compared with A/G Radio at a small airfield, therefore students will generally take longer to go solo. I remember a number of students who's actual flying ability was easily good enough, but who's first solos were delayed because their RT wasn't good enough to be 'let loose' at an international airport.
Previous passenger experience - While a student won't have logged any actual flight time from this, any experience of being in a light a/c, watching someone else fly (and quite often having had a go at the controls), being in the environment, listening to RT etc, is a huge head start when it comes to learning yourself, and therefore will get to solo stage much quicker than otherwise.
Simulator experience - There's a great debate about whether having used a PC flight sim before embarking on a PPL is a good or bad thing (it's generally accepted to be a bit of both - students pick up the basics of general handling quicker, but struggle to stop looking at the instruments and often forget that the a/c has rudders!). On the topic of first solo though, I've found that students with lots of PC Sim 'hours' will generally get to first solo quite a bit quicker, although for the remainder of the PPL course there seems to be little difference
Instuctor factors - numbers / confidence / experience / style - This is one that people might not think of so quickly, but again throws several more factors into the mix. Flying with too many different instructors will increase the time to learn, while sticking with the same one, two or maybe three is probably ideal but not always an option for students. A more experienced instructor will often send a student solo an hour or two earlier than a newly qualified FI, who (quite rightly) is likely to be more cautious, and some instructors by nature will tend towards the side of caution than others.
I'm glad the issue of 'whether 13 lessons can be covered properly in 4.5 hours' has been mentioned. For the JAA syllabus at a school where the lessons are taught in a proper structured manner, it seems almost impossible. I would hazard a guess though that acepilotmurdock or anyone else who went solo in a similar time, most likely had considerable passenger experience or at least sim experience before starting with the same 'zero hours' on paper as others with no experience whatsoever. I would also guess that the 4.5 hours were done very close together at a small airfield, with good weather and with no more than 2 different instructors?? Would be interesting to know!!
And I'm sure there are several more factors that I haven't covered!!
Hakeem, as long as you are enjoying your training and are learning something new every lesson then there is nothing to worry about
SB