The most important jiu-jitsu principle is taking what the person in front of you gives you.
The mechanics of a move, posture, or position are designed to support awareness based principles. Without awareness of momentum and energy in real-time I don’t care how good your mechanics are, your doing jiu-jitsu moves not jiu-jitsu.
A pitfall of intermediate and advanced levels is you can force things on lesser experienced grapplers that seasoned veterans and people with size, speed, and strength will nullify or take advantage of.
I did a web search to reference the following quote that has always stuck with me to no avail before Chris’s comment below revealed it came out of Saulo Ribeiro’s ‘Jiu-Jitsu Revolution’ DVDs :
“There is no proper position without the proper time.”