Indeed, it's usually very important to have the correct tool for the job, otherwise it's even easier to damage parts. Sadly, the aircraft I'm working on has a lot of different size-types in it, making finding the correct tool very interesting. You usually need 2 or 3 tries to just find out whether you're dealing with either a metric, imperial, British Association, or some other type of bolt... :S At that point, the bahco (or adjustable spanner, as you probably call it) suddenly becomes a very attractive (but still very wrong) solution...