Update on what I said before re using TOS for calendars study.
I don't use TOS myself, I relay on my apps to study trades or to verify statements made by others. Lately I spend much time on time spreads and today I fancied to check myself with TOS.
I believe I said TOS is an app that can be used for time spread studies bc it has abilities to manipulate IV of individual legs. My assumption was that those TOS' IV manipulations work similar to what I do. I was wrong.
IV changes made in TOS affect only t+0 line and, nothing else, not the price, not the whole risk graph. This makes study harder, not impossible but much harder and TOS' graph outputs might cause confusion.
Likely those who uses TOS for those purposes is already know about the issue, and for one who doesn't the thing has no weight. I just was not aware of that before.
Pic: Individual leg IV adjustment feature in TOS.