That's why I decide how much I think something is worth to me in advance, decide my maximum bid and once placed in advance, I leave it be.
The only exception to this is the last auction I took part in, where I'd set my budget but wanted several items. I had some 'left over' from my first successful bid so used the live online bidding to go for a subsequent lot. Despite being tempted to go rather over my budget I was the underbidder. A salutary lesson for me!
I do feel there's scope for auction houses to do a 'roll over' scheme, where if you don't spend all of your first bid, the remainder is bid against another item.
But my getting carried away last time is I guess precisely why they don't!