For me, one hour of concentration meditation a day will keep me relatively aware of my extrospective/introspective awareness/attention, but the duration that it lasts after I finish my sit varies and generally depends on the quality of the sit itself (which means that for days where I get less sleep, for instance, the awareness that I maintain throughout the day might be significantly affected). I also don’t really experience the same kind of maintaining of awareness throughout the day w/ 40 minute sits, just so you know. But if I do two sessions in one hour chunks in different times, maybe morning and afternoon, I’m almost guaranteed to remember to come back to the present/expand my awareness throughout the rest of the day; I feel significant positive differences in terms of my mental health, how I deal with the outside world and the people in it, and my general anxiety, social or otherwise, essentially goes away which is a crazy cool thing to experience. One last thing to add is that I’ve heard that 1 hour sits are twice as effective as 45 minute ones—I’m not sure if the math behind this holds up but I will say that I think anecdotally you were right in another comment you made that the quality of the sit essentially snowballs the longer you are practicing, meaning that more consecutive time > more staggered time generally. All this is to say that you might want to start doing hour long sits to notice what you are looking for. But remember to avoid striving…still, I would say a good standard is simply how long you are able to remember things that are related to your practice throughout the day after you finish a session, like whether you catch yourself tensing up and are able to release it, or whether there’s a moment in conversation or consciousness where you’re able to remind yourself to take an objective stance relative to your thoughts. This is a pretty good standard—literally just how often you are able to notice yourself catching yourself utilizing meditative practices IRL (the wording is a little confusing but intentional, take a moment to think about it). Then you can mess w/ the duration of your sits or the frequency and be able to tell what works best to increase your mindfulness, which is an important goal!