So I am learning New Orleans by Eugëne Bozza and I noticed that there is no key Signiture and it is simply written with a bunch of accidentals. It is also in 4/4 shown as Common time and some of it is in 2/4 but nothing unusual and for the entirety of the beginning section there are no bar lines. Is this how he notates all of his pieces? Or just this one to bully bass trombonists?

Bozza is an equal opportunity instrumentalist abuser. His “Giration” brass quintet was a bear for me to sight read. It didn’t help I was covering the tuba part on bass trombone. Both the C and Bb versions of the trumpet and the horn parts had the same key signature (none).

Both things are pretty common for 20th century compositions. The unmetered spots are cadenza with minimal piano. It’s a nice piece. Enjoy!

For music where any note is just as likely to need an accidental as not, key signatures tend just add another layer of complexity and doubt.

No key signature and all-accidentals-explicitly-notated is the convention for atonal music and makes sense for highly chromatic tonal-ish music.

In the age of human-copied parts it helped make errors between part and score less common... and easier to spot when they occurred.

Your instrument is non-transposing but for transposed-instruments the practice reduces the mental gymnastics of copying and checking parts.