I have to disagree with your disagree !
Nothing hammers the tear drop harder than a full range of motion extension. You talk about strain on the knee....would 505 lbs not be strain on your knee ?? Really...lets think about it...your seated...back supported..and all you have to do is worry about extending your leg. If you're worried about tension or strain then go lighter but rep out like a motherfukker.
I have never heard of someone saying that extensions were and are a waste of time
I have NEVER had a knee injury..and I've lifted some god awful amounts of weight with my legs...and I make a point to do at least 5-8 sets of extensions at the end of each and every leg smashing workout. Just sayin'....
it has its place, but like you said that teardrop. he said size and i'm guessing strength as well, since who doesn't want to get stronger. i just don't believe leg extensions are a good assistance exercise that can carry over into squats. it's like doing tricep extensions (more suited for a shaping exercise) to correlate into your bench. leg press, hip squats and even a sled drag backwards really hit your quads and would carry over well into a squat.