I used to do it a lot more when I was younger but honestly lately I've only caught the one legendary (Like Giratina in Platinum and Reshiram in Black) with the Master Ball the only time where I've tried without a Master Ball lately was with Uxie in Platinum I tried Sleep,Low Health and Confusion and nothing..I Used So Many Balls and Not even to close to one shake..it eventually knocked itself out because of confusion but it's not like sleep helped anyway it seemed :/..and that's why normally I don't do it..it takes an awful lot of effort to do constantly..

Edit:I Just remembered It was required to capture the three legendary birds (Moltres,Articuno,Zapdos) in Pokemon XD to finish the main story..It took me two tries to do it.

I rarely use my Master Ball, I typically have a knack for catching legendaries within the first few balls- it's pretty rad. ^ ^