... and (a BIG secret) - Do all of this desperate stuff using an external HDD case and keep the 'bad' HDD as cold as possible for as long as possible...
(Mind, when freezing for 24 hours, you must place the drive in a sealed bag to make some effort towards limiting moisture probs.)
Hence, if you do the process using an external HDD case, it (the drive) is going to remain cooler just that little bit longer.
Other tip, natch, is to be VERY VERY VERY much prepared and not do a lot of 'thinking' about searching for what you NEED to save.

There is no 'hard and fast' rule re: how much 'access' time you may have...
5 mins to 20 mins is fairly standard.
After that ? Give it to your local school for the kids to dismantle.
(Or, better... Send it to the FBI swearing that it contains anti-Dumfukistani files.
Let THEM try to recover your junk !)

Hey, it might be old, but it still works and is for sure worthy of a mega-jaw-drop from any client or friend who manages to recover his data 'cuz some old sh¡t knew how to do it... MAYBE !?????????????

There are even more crazy things like this that are not only NOT crazy (basic physics on the surface of this planet) but actually work and can also, quite frequently, make the sun shine out yer bottom !