I think it’s less important whether you feel absolutely confident vs. are making a guess, and more important that you communicate your level of confidence in words.
I usually won’t make a guess without saying it’s a guess. If I’m unsure but leaning towards something, I’ll be like: “I think this is probably X but it could be Y, please correct me if you know more about these two species than I do.” and then I’ll make the official ID as “X”.
In other cases I might be like: “I think this is X because (my reasoning / referencing evidence in the photo and/or range / habitat discussion).” and I try to use words to communicate my degree of confidence, i.e. “I’m virtually certain this is X” or “I am strongly leaning towards X” etc.
I’m always open to disagreement, but I think the more confident I am, the more evidence I need to be convinced to change my ID. I try to communicate my degree of confidence, as a courtesy to other users, so that people can know when to chime in.
I really love when other people do this because it makes it easier for me to know when I have something to contribute. If I know a little, I’ll happily chime in in a discussion where the other people clearly have no clue what the species are. However, I’ll be reluctant to butt into a discussion where the people have expert-level knowledge and I’m a n00b.