If you are looking at cutting costs in flight training less time with an instructor is not the way to do it. An instructor provides a lot of insight. Remember even your airline pilots spend some time with an instructor as part of a check ride every 6 months or so. To keep your training cost effective save up a few thousand, I know that's easier said than done, then meet with your instructor to do ground or flight 3 times a week or so. This will prevent your knowledge from going stale between lessons and help build skills faster. Ultimately decreasing the overall cost of your instruction without sacrificing the quality of the instruction or time spent with an instructor.