Absolutely. Sometimes there are occasions when piling in in the biggest size possible is what you should do. This is usually because of some news.
Didn't Laurie Inman do this when he was just starting out as a trader ?
He listened to Trichet and was very certain there was going to be a shock IR decision...
He wired his entire account into one trade... there was indeed a surprise decision... and he made about 200k in a couple of minutes ...
I could have dreamt that, but I'm pretty sure I read it in an interview.
If you've got the balls and seriously trust your own judgement, that's how you make big money in this game.
Of course you could wipe out just as quickly, but it goes to show there are some people out there doing it and cleaning up ...
I'm not advocating this style of trading and I certainly would never do it.