If you're going to use this technique, you must only train with people who are polite enough to always bow back at you. This generally means your kohai, or juniors (see below).
When the opportunity presents itself, bow deeply and slowly. When you're down there, stretch it out. Milk it. If you think you can get away with a full kneeling bow — not an entire tea ceremony, but something close to it — go for it and oblige your partner to follow suit. If you suspect that you are being watched by a third party, come up quickly at the end — it's that acceleration that makes it appear that your partner was the one who was dragging it out.
If you are training with an uninformed (especially junior) partner, this is an extremely reliable time wasting technique because it exploits the irresistable force of centuries of time-honoured etiquette and tradition.
If you are training with an informed (especially senior) partner, the techique is doomed to failure because of all time wasting methods this is the most transparent. You'll know if you have such a partner because the first time you try the prolonged bow they will come up well before you do. The second time you try it you may find yourself being attacked while your head is down.