whatsapp_web_groups/m22_planning/views/planning_slot_views.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="planning_view_pivot_inherit" model="ir.ui.view">
        <field name="name">planning.slot.pivot.inherit</field>
        <field name="model">planning.slot</field>
        <field name="inherit_id" ref="planning.planning_view_pivot"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='allocated_hours']" position="after">
                <field name="real_working_days_count" type="measure"/>
            </xpath>
        </field>
    </record>
</odoo>