My personal opinion on code tests:
The longer the test is, the better. Code tests shouldn't really be finishable in the 50 min alotted, if they are, placements are reliant on time bonus/not screwing up questions alone, not on the overall skill level. (we finished a 7 question test in around 20 min with a 2 min something solve and lost because we screwed up transferring a question to the answer section. If we had the opportunity to continue solving questions and getting points to the end, the results might have been different. The whole test was also only math besides the time, so that any team with minimal practice could've perfect scored the test)
They should cover everything on the rules at least once and emphasize the aristocrats and have a few patristocrats/xeno to seperate the top teams. Depending on difficulty there should be at least 15 questions, preferably more.
Also having ample room to work with is also important. Personally I feel like toebes wastes alotta space that can be used to provide more room (like use the vignere format) for aristo/patristo/xeno.
Questions should also not be too long. For the monoalphabetic substitutions, on toebes the cipher shouldn't exceed 3-4 lines. After that, the cipher becomes more of filling in quickly instead of recognzing patterns and words.
They should also be solvable... i've seen tests where ciphers were nearly impossible to solve. If nobody solves anything, that's not a good thing no matter how much you enjoy seeing everyone suffer.
In terms of letter frequencies or whatever, I don't really care too much if they provide frequency or not. Personally I don't think it's a bad idea to omit them on at least some aristocrats or whatever just to test you can live without them. Providing K1/K2 i'm also neutral about, although providing keyword is a bit too much infomation given away.
Anyways sorry for the long post, i've just seen some tests that I wasn't particularly a fan of. Basically use toebes, don't make anything ridiculously impossible/long, and have a good mix of questions, and you should be fine.
South Woods MS/Syosset HS '21
Favorite Past Events: Microbe, Invasive, Matsci, Fermi
Events!: Astro, Code, Fossils
Div C medals: 26