My , unfortunately now deceased college friend Albert, told me about an experience from his high school days in Chicago. Albert did Judo and Jiu Jutsu and had received a brown belt at the time. He exited from a local ice cream parlor and, being the urban survivor that he was, immediately noticed that there were two fellows following him. So he threw the ice cream down and started to cook down the block... But as he got to the corner he said to himself "Wait, I've got a brown belt!" So he turned and met the first attacker with a picture perfect koshinage which laid the guy out. Whereupon the other guy hit my friend Albert with a brick and knocked him out.
This is illustrative of the points made by several of the posters here. If you have a number of attackers you have no time for locking techniques. They take too long to apply and generally leave you too commited to that one particular attacker. Only if you can get one of the attackers quite a bit closer to you than the others can you execute a technique like shihonage.
Every technique has a series of beats. A real fight is like music that is playing very fast. Most of the beats are 16th or 32nd notes. The only really reliable techniques for a fighting situation are those that can be executed in one single movement taking one, one and a half or at most two beats. Anything else is too slow. That basically limits you to techniques that come off a direct entry (Irimi). Ikkyo can be done that way, but in a real fight usually the ikkyo is applied as a joint lock to the elbow and functions to take the joint out. A technique that only dumps an attacker without creating some level of dysfunction may be used strictly to buy a little time if the next attacker wasn't giving you enough time for a definitive technique. But really anything that allows an attacker to get back up and take another shot at you is risky and should be used sparingly. Most randori is really a practice of disguised atemi. Each technique should effectively take out one attacker in one beat or two at most.
That said, I don't understand the comments about not being able to do full speed randori in partcice because the techniques are too dangerous. Kihon Waza are specifically designed not to be injurious. You can take a full speed shihonage ukemi as long as the nage places your hand against your shoulder and does not stretch out the arm in the breaking position. All of our techniques are meant to be executed full speed without injury to the partner whether its one attacker or several. Most of the injuries in a randori happen when two attackers collide or one catches a flying heel as another takes a fall.
[Edited by George S. Ledyard on August 8, 2000 at 11:38pm]