It took me from Jan - Jun back in 2003, so it is possible to do in 6 months. I mostly had 2 lessons a week (Sat morning and Sat Afternoon) with the occasional Sunday/mid week lesson to make up for cancellations.
As others have said it comes down to how flexible you can be in taking lessons at short notice when you get a nice days weather. It also depends on your school/instructor(s). I had to delay my first solo flight for a week because of weather (wind approaching xwind limit), but rather than cancel the lessons I had booked my instructor took me off to do some basic navigation stuff. Then had the weather close in when waiting to do my QXC, as a result I got most of my test revision out of the way before the QXC.
But I know of people at other schools who had lessons cancelled because the weather wasn't suitable for the flight that was planned, despite being suitable for something else which would be just as valuable.