Is the user attention required or not?

We are developing 'Work Experience' module. You can see the screen as wireframe attached here.

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Scenario:

  1. The User entered information in 1st block.
  2. After that, he clicked on '[+ Add Work Experience]' button to enable 2nd block 'Work Experience'(you can see in pic)
  3. But he didn't enter anything like just empty(2nd block)

my question is-

When I clicked save button, should I show validation errors in 2nd block? or ignore the 2nd block and save 1st block only?

My thoughts on the user perspective, what is the use to show validation errors in 2nd block as it is empty. With this validations, the user again need to work or spend some time on either fill the fields or delete the 2nd block

My observations in a few applications:

Mobile: While creating new contact number in mobile, I added multiple fields like home, office, fax, email, email2 ...by clicking on the (+) button of each row. But I entered the number only in the office field. Finally, I tapped the Save button. It saved successfully. When I clicked to edit the number, whatever I clicked before like home, email,.. these are reverted.

Google Contacts: https://contacts.google.com/ I added multiple fields but entered a few fields and pressed save button. Without asking or showing any validation errors it is successfully saved.

The above examples are not mandatory fields. Here my screen has mandatory fields and kind of widgets and overall one save button.

Please share your thoughts and any example if you have seen anywhere. If I am thinking any wrong direction please let me know your suggestion