Interrail exit/entry days Extra travel days?

Hello,

I'm planning a trip with an Interrail pass and am now at the point where I want to determine the number of travel days. However, I'm wondering: do the trips from and to my country of residence count as extra travel days?

For example: I travel from Berlin to Barcelona, ​​then back and forth within Spain for 4 days and then travel back from Madrid to Berlin (realistic possibility excluded for now, this is just a theory^^) – do I then have to book 6 days or just 4?

Thanks for your answers!