I've had one person out of about 25 that have tried that has been able to do the whole thing. Many can get the spongy tip in their throat but taking the girthy, fully hard shaft meat in the throat is too much for most. So most get about 5 or 6 inches and tap out. Some girls basically just suck the tip lol. What works sometimes is getting it in the throat while it is still soft and letting it expand but it usually pops out when I get hard.
So, for the most part, I am just too huge to be deepthroated balls deep. But it can be done.