Sonicmario,

are you aware that parking the heads of a disk is wearing your disk down until it will fail ultimately?

There is no general answer to your question as your disk may not obey to certain shutdown commands of your operating system on purpose.
This behaviour is supposed to prevent excessive wear after some disk manufacturers were parking heads too often.
To overcome this problem buy a USB hub with individual power switches.

You are not running the ISS and you are not programming ICBMs. You are not providing system relevant services to the world.
There is not need for your in terms of excessive data protection by using backups.

But when reading your contributions there are strong signs that you are suffering from a data loss phobia which might be the origin of all of your questions. In a general sense you might be suffering from fear of loosing something.

When this fear is manifesting in a storage context you will need to learn that regardless the measures you take you can always fall victim of data loss. You have to accept that.

If you don't change, you might end up flying around the world putting 2,5'' disks into bank safes on every continent, returning next week to verify that their content did not change.

Do all 2.5" HDD models and brands have a self-parking system to protect the HDD from minor knocks? knocks on the side of the enclosure case with the movement of the hand when removing the USB 3.0 cable from the PC the case moves to any side of the table with the knock

_________________
Joep - http://www.disktuna.com - video & photo repair & recovery service

People with two hands are able to hold the enclosure with one hand while pulling your USB 3.0 cable with the other hand either out of the enclosure or out of your computer.

You are fabricating artificial problems that nobody cares about.
Futhermore you are ignoring my solution for your problem.

For information on maximum allowed G-force applied on your disk contact the support of your hard disk manufacturer.

Is there a big difference in the impact of the hand on the case of this 2.5" HDD on the table vs. hdd + case it falling on the floor?
Do 2.5" HDDs have any protection against moderate impacts? Or do any impacts cause the reading head and arms to touch the disks?

Common sense will tell you.
Are you a spec sheet reading denier?

I don't have much technical knowledge about the internal functions of 2.5" HDDs.
I have these two models from 2013, models WD10JPVX-08JC3T5 and HGST HTS541010A99E662 and I couldn't find a datasheet.