It may seem like anyone can arrange a piece of music, and to an extent this is true. However, there is truly an art to arranging beyond just writing out parts for different instruments. Numerous considerations come into play: pertinent information on the instruments (including but not limited to range, available colors, tessituras, muting, extended techniques, transposition, etc.), optimal blending of instruments, possible doublings, fatigue issues, etc.. Then we come to the artistic side: adaptation of the material, style changes, melding/mash-ups, etc.. Finally, all of this needs to be run through filters of: usage, performability, sight-readability, potential rehearsal/performance issues, audience appeal, etc.. To be a useful and artful arranger means giving thought to each of these aspects and many more.