A great tip for making a large number of sandwiches efficiently is to do the following:

1. Place a loaf of bread in the freezer for 10 minutes (this makes it easier to slice).
2. Remove the crusts to leave a single, crustless loaf.
3. Cut ½” slices lengthways (so you have huge rectangles).
4. Butter each giant slice and put filling on one side.
5. Make a sandwich and then slice into fingers.

Job done.

Note: it’s a good idea to use simple loaves (white, wholemeal, etc). Avoid textured loaves.