The butter will taste exactly the same as straight from the packet if it has been in the fridge the whole time, as long as butter is cold it will taste the same whether it is in the packet, on a sandwich or buried 4 months in a swamp (ehm yes this has been done
and replicated
)
Some breads will go always go soggy other breads will only go soggy with certain fillings/toppings. And to be fair to the guy I know to bread types with Swedish cheese that if wrapped in clingfilm and kept in the fridge actually tastes rather nice, in fact even better sometimes
Being from a poor and frugal background any sandwiches left from picnics and school outings went into the fridge to be eaten later, It works best when the bread is Limpa eller Fralla with butter, cheese and/or cheap smoked ham, mayo can work too but not directly on the bread but rather on the cheese or the ham. Tomatoes, lettuce, cucumber and peppers on top should be avoided...but I'd still eat it. Must say though my absolut max would probably be 5 days and no more...unless when totally skint as then I'd eat anything.
Although sandwiches will never count as lunch for me so most often I cook a mahoosive meal and then I have two dinners and two lunches, sometimes I even get two more meals out of it. But my friend she cooks proper meals for lunch boxes on the Sunday for the whole week, if I had a freezer I would do the same.
I is a girl so not sure on the man thing comment.