We are all different and so this is never to be forgotten. I have certainly known a number of people complete the PPL in a month or even less. I have known few PPLs who are objective when assessing their own abilities. I'm very cautious of those who boast of their 3 week licence undertaken without any previous experience. The vast majority of the rushed PPLs from zero experience lack too many skills and they pay for it later one way or another. Remember the world of flight of which you have no experience is very different than the world you know lots of from life on the ground.
The quick fix courses are usually provided by schools who do not expect ever to see the the student again and therefore bear no responsibility for them. This observation is shared with me by fellow instructors all over the world. It is no coincidence that the world wide 60 hours course average is the same in the UK. Judgement and decision making takes time to develop and it is usually the main difference between 45 hours and the sixty hour average. Remember the sixty figure is an average so many take much longer. If the individual has a background in flying - gliding and microlight flying etc then to complete in weeks weeks rather than months is definitely a reality.