How does the scoring work and has it changed recently? I ask because since one or two releases I've been unable to get anywhere near my 32k score (untimed), maybe around 20k and I've played quite a bit. I also noticed that the multiplier isn't going up each time the bar is filled:

1x, 2x, 2x, 3x, 3x is about as far as I have been able to see, maybe this is why.

I don't know if this was always the case. What's the point of filling the bar if at the end it isn't going to change or does it do something else?