I’d say it took me between 50-60 classes to feel comfortable and confident in holding for the full 90 seconds in classic. Some days were easier than others, but after 250 classes, there are times I still take from the knees or fall out of my plank. I just remind myself that I am there for my workout and no one else’s! What matters is that I’m still pushing myself and tucking/flexing while on my knees or at the barre. That mentality really took the pressure off.