Sebastian Vettel believes this season's Formula One title chasers face a "very tight call" deciding whether to go for broke or settle for second best during a race.

Vettel's crash in the Belgian Grand Prix four weeks ago followed by Lewis Hamilton's opening lap accident in Italy brought into sharp focus the split-second judgments being made.

Vettel t-boned Jenson Button after attempting a manoeuvre derided by the reigning world champion, one that sent him into retirement when he was running second.

At Monza 13 days ago, Hamilton pushed too hard too soon by going for a gap that did not exist as he tried to dive down the inside of Felipe Massa on approach into a chicane, which resulted in a broken suspension.

The question now for Vettel, Hamilton, Button, Fernando Alonso and championship leader Mark Webber regarding bravery or sensibility at any given moment comes down to the individual at that time.

While a driver will always want to go for a win, there has to be a time when playing the percentage game becomes paramount.

"Put it this way, if Lewis' suspension had not broken then nothing would have happened and no-one would have talked about it," said Vettel.

"In his case it did break, it all went wrong for him and it did not look very nice after the race.

"It's a very tight call from inside the car, and it depends on who you are, your driving style because some drivers try, others don't.

"You need to look at the risk, whether a move is possible or not, and if it's not possible you don't try.

"But sometimes you think it is possible, you try and it doesn't work.

"Look at my example in Spa. I don't think I did terribly much wrong, but it ended up the wrong way.

"We are all human, we all make mistakes, and if we make them on a Friday nobody cares; if we do them on a Saturday people do care a little more, and if we do them on a Sunday, depending where and when, it is a big thing.

"That's correct because the race is the time we need to deliver.

"In the end the quality of a driver comes down to his speed, his consistency, and the amount of calls he gets right."

Vettel comfortably finished top of the timesheets at the end of yesterday's two 90-minute practice sessions and is arguably now favourite to clinch his eighth pole of the season in qualifying today.

If the 23-year-old does so, much will then come down to his start off the line as to his chance of success on Sunday, and Red Bull have been remarkably poor of late by their standards when it comes to pulling away off the grid.

Vettel is adamant there is not a problem, insisting that "things have come together which have resulted in a bad start" either for himself or Webber.

"I don't think it is something we have lost, it's maybe the others have caught up and we have lost our consistency, that robustness to get good starts all the time," added Vettel.

"It's been a little bit up and down, but I'm confident we'll have good starts again. I can't guarantee, but we'll try."