Bill Leavitt was one of the great guitar teachers at Berklee. His books devised for learning jazz guitar and reading are so important.

With C#,E,G,Bb,C,D you could remember the tuning if you see the C#,E,G,Bb as a C# diminished seventh chord subbing for an A7b9. If it's an A7b9, the C could be a raised 9th but it would clash with the C# (the 3rd) or it might be jazzy.
If A were the root, the D could be thought of as an 11th.

Different jazz tunings on guitar have been tried notably Carl Kress and Marty Grosz, from low to high, Bb,F, C, G, B, D. (Note the bottom four strings are tuned in fifths like a tenor banjo and the top four are tuned like a plectrum banjo).

DADGum it!

Frank