How much flexibility to railpasses allow?
 

In middle of january me and a3 friends (we we will all be 19yo students) are hoping to go backpacking in europe.

When my dad did this as a youngster, he got a railpass and completely winged it. However, this was before compulsory reservations were brought in.

Is it possible to still wing it? Can reservations be made a couple of days in advance, or do they have to be weeks in advance?

price isnt a big issue as i think ive accurately come up with a cost including all reservations, i just want to know if winging it is realistic.

We hope to travel
Paris -> Brussels -> Amsterdam -> Hamburg -> Berlin -> Contiki tour to Hungary -> Lichtenstein -> Venice -> Rome -> Pisa -> nice -> paris.

but we want maximum flexibility from hungary onwards, are we being realistic?

Yes, you can make reservations on some trains a few days ahead. the secret for you just MIGHT be in avoiding trains that REQUIRE seat reservations

You can be flexible because you four will be the only people on the trains and in the hostels. I made a one month grand circle around Europe a few years ago in January. I made my night train reservations on the mornings that I traveled that evening. T-4 couchettes are perfect for your group. There is virtually nobody on the trains. For an illustrated introduction to trains in Europe see http://tinyurl.com/eym5b.

Wing it all the way.

@Dukey, seems like most of the trains from hungary (budapest) back to paris require reservations. And im not sure i want to risk missing trains on the way to berlin, since i need to arrive in time for my tour. So i will probably reserve those couple.

@spaarne, thanks a lot. really put at ease some of my concerns and the website is really good.

contiki tours seem to spend 2 or 3 nights in each place, so this is our rule of thumb for when we backpack. or do you think we will need more time?

Each country has its own rail system with different types of trains and tickets. In Germany, a rail pass gives almost complete freedom to hop on or off any train.
Some countries are now more complex but, in mid-January, you should have absolutely no problems anywhere. It's probably the quietest time of the whole year for travel, apart from a few services aimed at people on skiing holidays.