Thanks. On the tutorial page I saw this example on custom actions:

from odoo import fields, models

class TestAction(models.Model):
_name = "test.action"

name = fields.Char()

def action_do_something(self):
for record in self:
record.name = "Something"
return True

Why is for loop used here? Do we need it? Because we're modifying very specific record as I understand it.

For example, there's a button "Action Something" in form view of some record. It doesn't refer to other records. We don't want to set "name" attribute for all records, only this one. I hope this makes sense. Would it be okay to do self.name = "something" in this example?

Or maybe loop is here because this action can be applied to lots of records as once?

Thanks. On the tutorial page I saw this example on custom actions:

from odoo import fields, models

class TestAction(models.Model):
_name = "test.action"

name = fields.Char()

def action_do_something(self):
for record in self:
record.name = "Something"
return True

Why is for loop used here? Do we need it? Because we're modifying very specific record as I understand it.

For example, there's a button "Action Something" in form view of some record. It doesn't refer to other records. We don't want to set "name" attribute for all records, only this one. I hope this makes sense. Would it be okay to do self.name = "something" in this example?

If the action linked with button on form, you can use self.name = "something" without loop.
But sometimes you need to add this action to Actions menu as server action to apply the action to selected records from list view so you will write the server action

<record id="lunch_order_action_confirm" model="ir.actions.server">
<field name="name">Lunch: Receive meals</field>
<field name="model_id" ref="model_lunch_order"/>
<field name="binding_model_id" ref="model_lunch_order"/>
<field name="binding_view_types">list</field>
<field name="state">code</field>
<field name="code">records.action_confirm()</field>
</record>

As you can see the action_confirm methods called for selected record from form view and if write your code of method without loop then you will get an error.

So the summary you cannot use it without loop but its recomended to use loop.