It helps to get some consolidation in your training. When I sensed I was getting close, I flew every evening from Monday to Thursday, went solo on the Thursday evening second flight (at 10 hours PPL training, but with some previous gliding experience).
If you only fly occasionally, it will take a lot longer. However, your gliding experience will help, as you should at least know the basics.
It's not a race, but slow progress because lessons are spaced too far apart can be demoralising and will definatly result in a far more expensive licence - three steps forward each lesson, but two steps back in between 'cause you have to re-learn so much with such big gaps between lessons.
SSD