Upvote:2
Nobody will check later. Indeed, they want to be sure that you have a place to stay. If you have booked an hotel, it means you certainly have funds to cover your stay. Ok some will tell that some hotels can be booked without a credit card but for a lot of hotels, you can't perform any booking without a credit card.
So the answer is that I don't think it will affect the visa validity. As long as he has a valid booking, it will be ok.
Also keep in mind that booking checks are randomly performed (probably when they have a doubt) and certainly not systematic... It would be too complex to always perform it.
Upvote:2
You get in contact with immigration extremely rarely. They most certainly won't chase every traveler within their borders, in 2015 there were 14.3 million Schengen visas issued, it's quite near impossible to keep track of that many people across 26 states without very seriously compromising freedom of movement of citizens as well (you would need to check paperwork at checkpoints Soviet Union style). It is estimated that every year people make 1.3 billion crossings of the EUβs internal borders. DB German Rail alone has a ridership of 1.9 billion yearly. Checking that many people just to fish out the very few who carry a visa and even fewer who would be violating their visa terms just doesn't make any financial sense.
Also, there's no reason to. They want you to leave at a given time and to not work but what do you do and where you go between your landing and leaving is really a non-issue.