Not really.
Some programs will remember where the last path used was and will revert back to it so you'd only have to select it once. Some programs (like Microsoft office programs) have an option in the settings to set a default save location, some programs might have a registry setting and some programs will just revert back to where ever the hell they want each time you try and save.
It's possible to move the location of your documents folder so anything that tries to save there as default will save to the new location, but I wouldn't recommend putting your documents on an external drive, if you have a 2nd partition on your internal drive moving the documents folder to that is fine though.