training from Switzerland to Italy

When are you going and where in Umbria?

What are your primary criteria - fastest, cheapest, least connections, most scenic? The railway system websites (sbb.ch/en) should give you the fastest routes with several choices.

I think it will be an all day trip of 11 to 12 hours and several train changes.

As the others have mentioned, that's going to be an all day trip. You didn't say what method you were using to check your options?

I had a brief look at the Bahn,de website using an arbitrary date and Interlaken Ost and Orvieto as the stations. That trip seems to range from about 9H:27M with 4 changes to 11H:14M with 3 changes. Those results could change depending on the stations you'll be travelling from/to and the dates.

Although that will be a long travel day, sometimes that's the best option.

For comparison, our train trip from Lucerne to Lucca took 8 hours. Can you break it up and spend a couple of nights somewhere along the way? Or is it imperative that you get to Umbria on the same day? Otherwise, just prepare for a really, really long day, and recover in Umbria. Not a bad place to rest and regroup!