I wish I could learn how to interrupt people. Often it feels like interruption is the only way I'll ever get a single word in but I feel awful doing it.

Usually I like to wait for a brief pause in the conversation, but with some groups of people such pauses either never come or are so brief I can hardly react fast enough to catch it.

I'm the opposite. I have a bad habit of interrupting others, and find it hard not to.

I would be curious of hearing more about the dynamics of this helps? I have a talk (honestly not a very good one: this was my first virtual talk and I wasn't confident in the topic and I did too much preparation on the tech and not enough on the talk; but this is the best part of the talk) at a conference recently about working from home where I spent some time using interrupting of people as a more in-depth example of cultural crosstalk in action: https://youtu.be/W5PlZqdMR5w. A core thing to appreciate--and there are studies on this from the field of linguistics--is that it takes so long to begin speaking with so many muscles and so much mental effort (in the same way it takes way more time than you would expect to just move your arm, and the studies that show you had to have decided to move your arm before you "thought" you had) that I assure you: no one who is interacting "fluently" in that discussion dynamic is waiting for pauses... they are anticipating (likely automatically, with no conscious processing or anxiety about it) the end of someone else's thought and are just better at the prediction or better at aborting the process if they are wrong (or imply are OK with incorrectly predicted interruptions happening occasionally and don't take it as an embarrassing faux pas).

(Not in the talk, as the talk wasn't actually about any of this, despite how much time I dedicated to it... it was about working from home.) I do feel like there is a real problem here in that we have a systemic issue (in addition to some people who are just directly assholes who don't want to hear women speak; I 100% appreciate that these people, unfortunately, exist) where we have taught women to be subservient and to not speak up for themselves in lots of contexts, even if the pervading culture of the men around them involves a very short short turn delay, and one aspect of this is "they don't interrupt people"... men do interrupt people, as part of simply being taught that our new information is de facto valuable, and we thereby have an advantage over women. It isn't because we are rude: it is because we have a different dynamic ingrained in us by our (joint) surrounding culture and it is absolutely unfair and biased against women. And so we need to be cognizant of this and do it less with women and even actively "make space" for women to speak. But, at the same time, we should be training women that interruption is ok and that not only will they do better if they interrupt but the entire team might benefit from their interruption, and that being good at the predictive modeling is a conversational skill everyone must have anyway and for which there is general value if you get better.

I know I'm not a communication expert so I have to take my own observations with a grain of salt, but I would say I only have trouble conversing with maybe half the population because of my inclination to not interrupt. But I've noticed no gender or geographic trend to this. Some groups of men or women I'm able to converse with smoothly, as they seem to deliberately pause to let other's speak. In other groups, I'm hopeless. Perhaps it's an introvert/extrovert divide (I'm skeptical of that dichotomy, but that's another can of worms.) I can talk comfortably one-on-one with my mother or any of her sisters, but put two or more of them in the same room and I'll not get a word in edgewise. For that matter, I also feel fine monologuing in front of an audience and always have, so I think it's not simply a matter of shyness.

I find myself wanting to say something, and never getting to get a word in, then I quietly morn the words I never said :-(

The easiest way to not be an interrupter is to be quiet until it's your turn to talk or when someone asks you a question. Whatever you have to say can wait, no matter how relevant it is. If it's important, write it down for later. This is not that difficult.

In some groups, you'll never get your turn. As an experiment, I once counted how many half-second (or more) pauses there were in a meeting I had to attend at work. In half an hour (the duration of the meeting), there were none.

On the other hand, I agree with you. I see some people saying "interruption is ok". I disagree. It has to be an exception reserved for keeping the meeting on track. The normal course of things should be that everyone gets their turn to say their bit or to "pass". People who aren't able to wait for their turn or take too long typically will understand if you/the-manager have/has a brief chat with them later (or the person who called for the meeting should bring them back on track).

In my circle of close guy-friends it’s so common to just always crack jokes and banter that there are zero silent moments. In fact there’s often more than one person yelling over another person with a better joke or twist on a previous joke or some story. It’s like a bazaar.

You do need to time it right to get the word in, but you can’t wait for a silent moment.

It’s like merging on the highway. You can’t wait for all cars to stop. Have to time the merge correctly and force your way in, even if nobody is letting you in.

Social settings are not the same as meetings at work. I don't mind sitting back quietly and in fact prefer others carrying the conversations when in a social setting. My point of view above was only about official meetings. Work shouldn't be an environment where one can only be heard by being rude (interrupting).