Personally I'd only do a block payment if you can get a better rate. I taught in Denver CO for 18 months and their rates were about 10% less for a 10hr block payment.
If you want to get through in minimum time my experience was that there was a sweet spot which varied from person to person but the general rules still applied.
At one end of the scale we had students with huge bags of cash who wanted to fly every day - they'd be done in 6 weeks but would end up flying over 70 hours to get their rating.
At the other end of the scale were casual students flying at a low rate of once a week or every two weeks; they'd end up spending the first 30 minutes of each lesson re-learning what they'd forgotten and also took a long time to get done (if they didn't run out of interest first because they felt like they were learning too slowly).
The sweet spot I encouraged my students to follow was 2 times a week for the first 20 hours slowly increasing to every other day for the last 20 hours. People who followed this generally got done in about 2-3 months and about 40-50 hours.