There is no "correct" amount to lower. Different circumstances call for a variety of different solutions as far as any technique is concerned, including lowering. Such variations in circumstances would be:
Different figures or movements
Different partners
Your own ability and preference
Your surrounding environment
- Soical / competitive
- Crowded / empty floor
The music
For example, I would tend to want to lower more if I was dancing competitively, less for social dancing, especially on a crowded floor. I will lower more when I have more time to lower, such as when the music is slower. If the music is fast, I'll lower less, dancing almost more of a Rumba.
You get the idea. The main thing to realize is that the deeper you lower, the more power you have to you move (to a point of diminishing returns). Generally you will lower more when it is your goal to move bigger.
To me, the biggest question is not one of how much to lower, but when to lower. You should try to make sure not to lower immediately as you step on count 2, but to step on a straight leg first, and then lower after the beat (say, on the "&" of count 2). This will give your Bolero a stronger more picked-up look, as well as a softer, more continuous action through your check.
It is important to remember that Bolero is, first and foremost, a Latin dance, and as such it should reflect that character with the appropriate movement: Latin hip motion. Rise & fall which is either timed incorrectly or just overdone will limit your ability to incorporate good hip action. Good Bolero has a good balance of rise & fall and Latin hip motion, both in moderation.
Sincerely,
Jonathan Atkinson
www.ballroomdancers.com