Not trying to peddle copium (as Tristen shooting 3's at a 35%+ clip would definitely help his cause to stick with at least a 2-way contract), but fwiw there's a TON of horrific shooting going on in the summer league...even by guys that were known as very good 3pt shooters in college.
Perusing the box scores, most teams are shooting 25%ish, most players shooting a decent volume of shots are shooting meh/good at best. For example last night, min 5 shots attempted:
The Bad/Meh-ish:
Furphy: 1-8
Newton: 2-8
T. Alexander 2-7
W. Ellis: 1-6
GG Jackson: 2-7
J. Hawkins: 2-7
K. George: 1-5
P. Baldwin: 1-5
M. Jones: 0-6
C. Brown Jr: 1-5
J. Martin: 1-5
K. Johnson: 1-8
E. Bates: 3-12
P. Nance: 2-8
L. Miller: 1-5
R. Dillingham: 2-7
D. Nix: 2-7
J. Clark: 1-6
R. Sheppard: 0-5
The Meh+/Good/Very Good:
H. Tyson: 3-6
J. Wells: 3-9
A. Reeves: 3-5
J. Ford: 3-5
T. Funk: 3-6
B. Carrington: 2-6
J. Bernard: 3-9
B. Ellis: 3-6
N. Clowney: 5-8
J. Wilson: 6-7
T. Martin: 3-7
D. Knecht: 2-6
B. Hinson: 2-6
T. Hendricks: 2-5
M. Abmas: 2-5
J. Minott: 2-5
A. Griffin: 2-6