Earlobe stretching needs to be done slowly. If you overstretch, it's easy to create long tears around the circumference of the fistula (the skin tube that makes up the inside of the peircing). This risk can easily be avoided by stretching slowly — there's no point in stretching too quickly, because the subsequent scar tissue that forms after a tear is much more difficult to stretch.
If your lobe does tear, it's important to treat it properly to avoid follow-up problems such as blowout. After a torn lobe, immediately downsize — sometimes significantly — the jewelry to take all pressure off the wound. Allow it to fully heal before attempting to continue stretching. You may actually be pleased to find out that when you get back up to the size you were at that your lobe is actually a little thicker as well — but not always; some people may actually experience the opposite as Ashley writes,
"When my right ear ripped after I stretched to 3/4ths, I let it downsize to heal. It didn't get thicker than before and when I went back up to 3/4ths it got really thin... thinner than my left ear. I'm afraid if I stretch it larger it will completely rip because it's so thin."
The biggest key in stretching is to take it slow and listen to your body! Philip Barbosa adds,
"This might not be accurate, but when I was in college and stretching my ears seven years ago, in Toronto 0 gauge ears were not that common and usually noticed. My humanities professor told me a story about a tribe in Africa where the stretching of your lobes represented knowledge gained through listening. If done correctly, and done over time, you showed years of knowledge obtained from listening to elders with much larger lobes and much more knowledge than you. If you went too fast though, you would mess up your ears and look like someone who was passing themselves off as falsely knowing more than everyone else... the village idiot."