I have purchased a eurail pass (10 trips over two months). I will be  in Spain, Portugal, Switzerland and Germany. My trip starts in Spain on May 9, 2023. I have made all hotel bookings so know  exactly on what dates I will be traveling from city to city in Spain and Portugal .My question pertains to required seat reservations for Spain, and Portugal. I am aware that seat reservations cannot be booked online for these countries. It seems that I have to make seat reservations in Spain and Portugal  at either a ticket office or at the station. Do I run any risk of  not being able to make a seat reservation if I arrive in Spain and want to reserve a seat for Madrid 4 days later, as well as all other destinations? For the month of May should I worry or not worry about this?  Thank you kindly for your response.