I have always strived to be as totally honest as I possibly could, often to my detriment.
This 'lying by omission' thing is not so simple. I try to give a total and accurate answer to questions, but frequently get criticized for saying too much. NT's seem to like a short 'good enough' answer which for me is hard because the answer is rarely correct if I do that.
Plus other times, I don't want to tell them something, so I choose not to. If it is none of their business, and they choose to believe something that is not true, and I didn't say that, but I didn't correct them either, then why should I? I am not interested in policing what crap goes on in other people's heads.
My husband sometimes wants to know something and I don't want to tell him (because he wants to know every tiny irrelevant thing about every tiny irrelevant thing and I don't have that kind of time or patience) so he pushes it by vocalizing a conclusion that he knows is wrong and will upset me, thinking I will clarify with the truth, and he will finally know. I sometimes do, but I deeply resent those kind of tactics. But these days, I say 'think what you want' and drop it, if he lets me. He should respect my judgement about whether the thing is something he needs to know or not.
There is only so much responsibility I am willing to take for what others think. If I did not plant the false notion in their heads, then I don't have to clarify it unless I want to for some reason. This does not make me a liar, as far as I'm concerned.
I tell the truth because I remember so much. I remember what happened, and think of many possible ways I could get caught, and decide I don't want to deal with that. It is too much work for my overloaded brain to remember the event, PLUS the lie I told, PLUS who I told it to, PLUS all of the details that have to be consistent with everything surrounding the lie and the actual event. My mind aborts the idea and embraces the truth, even when unpleasant.
My husband has a hard time lying to me because I am that person who will remember that little thing he said on the bus five years ago that is not consistent with his lie, so will catch him. He lies, and does not remember. Stupid. He even holds it against me that it is not easy to get away with a lie with me - like I am the criminal and he is a victim. HAH!!
I do lie to him, and only to him, usually to protect my kids. I would lie to GOD, if there were one before me, to protect my kids. He never went to school and literally does not understand anything about grades, except that "A" is the best grade. If he sees a "B", he tells my kids that 'they will go nowhere'. So I tell him they don't get report cards at the new school, and he says nothing.
But to protect myself, I usually cop the fight rather than to lie. I get away with the lies because I do it so rarely.
On the flip side, if I really wanted to lie, it is unlikely I would get caught. I would spot the inconsistencies and deal with them making it harder for someone to catch me out.