1.) The prices are made by demand if a trains in emptyer you get cheaper fares. The saverfares or early bird fares are often not refundable or exchangeable (with Interrail or Eurail you get a mix of flexibility & money saveing )

2.) In Spain quite late usually just 2-3months in advance :/

3.) If you wanna stay flexibile (day of travel, new destination) Interrail can be a good choice as the cheap fares online are often non refundable or exchangeable fares.

Please Note Spain is not Interrail friendly as almost all trains need a reservation on top of the Railpass.

My advice if you have a fixed Route/shedule and you know you will travel for sure then it´s better to book Point to Point tickets (Carefull with the changeing Covidregulations i´ve lost 4 tickets because i couldn´t go due the Covid Lockdown & as the tickets were not exchangable or refundable I lost the money)

If you wanna be a bit flexible (However Spain with Interrail is not real flexible) i recommend to buy a railpass (Interrail/Eurail) + the needed reservations on top of the pass

PT-ther railway is named cp-check their site, its also complete in /en/. Nearly all prices here are fixed-except a few advacne for the IC trains. They also do their own railpass-for the whole country or for areas around the major towns. You MAY even get 50% discount off the normal fares-depends on your status, which you did not detail as such.

ES-the national railway is renfe and as seewulf already explains is notorious IR-UNfriendly. On the main axis MAD_Barca there are now also low-cost trains from RENFE (AVLO) and a competitior from FR-QuiGO- their fares are lower, these trains are not in IR.

RENFE also has its own rail'’pass'’ but its for a certain nr of trips-not days-it may work out a little cheaper as buying all tickets separately. Seniors can buy a '’carta dorada'’ for a few eur and then get 40/50% discount with it.

The advance discounts are only for the '’AVE/Avant=hi speed trains, other trains are fixed price. Around all main cities are extensive '’cercanias/rodalies'’ local systems, whcih are quite cheap and not in any timetable/planner, only their own special site.

Both countries, but ES much more, also have extensive long-dist BUS (named '’coach'’ by british) systems-these serve many more towns and are a bit cheaper as the trains. FLIX is just a minor player here- the main one is ALSA.es, but there are many others and there is not a centralized system.

IR mostly has its use when people make multi-country long trips. Alas, to reach this you have to pass FR of course, which is also not very IR-friendly (mostly named after ES as being the worst in it!)

I see that, I bought the Eurail and grtting surprise with extra charges when booking a reservation look at the foto that i am attaching, booking through Eurail  App, getting charged extra for Seat Reservation and Extra Suplement!!!

@antecoco Italy,France are two of the Countries that need reservations on their Highspeed services It´s mentioned if you read the informations pages of the Countries on Eurail/Interrail :/

There should be no extra supplement as “just” the Reservation. Every Railcompany decide on their own if and how much they charge from Eurail travelers Sadly France & Italy noted they are popular and could charge quite high reservations :/

See why: last week someone asked about last minute Barca->MADrid: I checked (I was incidentally in Barca then) and quoted lowest price on RENFE for the superfast AVE was 120€!

Now a tipical passday cost around 30€, plus RENFE charges mostly 10€ for the REServacion. Thats together only 1/3 of normal takings, so its quite understandable they do not ant anyone to use that for all seats. The supplmt for going over borders is far, far higher.

Inter/EUrail was nearly finished some years ago as exactly those 3 railways (and €*too) wanted to quit or have those superfast TGV/AVE/FRecce out of pass-use at all. This was a kind of compromise. Use the pass to what it is meant for: going slowly through undiscovered areas and not just skipping off a few capitals.

The 3-4 regular people going through all the same Qs that all newbees all make the very same-without even the idea to check if their problem is new or solved- have to answer this a few times every day.