Has anyone tried or done a calorie deficit of 0.3Lbs/1050 cals per week?

since one needs to eat 3500 less calories to lose one pound, one should lose a pound about every 3 1/2 weeks. it will work, it would be easier to do. it would mean eating 150 calories less per day, consistently, but at that low a deficit, there isn't room for a cheat day or cheat meal - it would be easier and more sustainable, and probably a bit easier on the body, too. the catch is you need to have to know how many calories your body actually needs - the general counts are only general, and most people who don't have experience logging and monitoring the results probably don't know how many calories they actually eat.

the problem is most people prefer to see results as soon as possible or they sort of give up... i'm often guilty of this even though in my head, i know better. but if i weren't also working on getting my blood sugar stable sooner rather than later, cutting 150 calories per day is what i'd do - it's a good idea.

I'd say it all depends on you and your goals. Everyone has their own pace as long as you can maintain it in the long run, and there's nothing to stop you from adjusting it later and seeing how it works.
It's better to start slowly but surely and acquire good habits in terms of nutrition and adjust as you go along, rather than start with a big deficit, feel that it's too restrictive and give up quickly.

Having said that, the only slight downside I'd see is that with a deficit of 1050 cals per week, i.e. 150 per day, you have very little room for error. If you miscount your calories or forget to add a few things, you could be out of your deficit easily.

But for me it would just be too damn slow, at the very beginning of my diet I did a 300kcal deficit per day just with food (so maybe 500 with exercise), it's very doable, over the whole day doesn't make a big difference (in the sense that you probably won't feel extremely hungry because you're eating 300kcal less), the results come faster while remaining in a healthy weight loss pace, never felt that restrictive. I wouldn't have seen the point of going any lower.

I did it for some time, looking at the data retrospectively. Calculated from weight loss, it was about that 150 calorie deficit daily, on average. But I didn't explicitly target that size deficit - just kind of went for "really small deficit".

Explanation: I usually calorie bank most days to eat indulgently now and then. Over about the first 4 years-ish of maintenance, my weight had crept up a bit, and I decided to creep it back down mostly by reducing the indulgences, and sticking to the "most days" calorie goal more consistently.

It worked fine. It was almost completely painless. Obviously, it takes a long time to lose a meaningful total amount . . . in my case 15-ish pounds in around a year. I wasn't in any rush, didn't have the spirit for a big calorie deficit, and was only trying to go from "jeans snug with Winter long johns on" to "jeans loose with Winter long johns on".

I was very experienced in calorie counting at that point, and very good at predicting my own weight changes (using personal history data) at a given calorie level. It'd be harder if new to counting, and relying on a calculator or fitness tracker for calorie needs estimates at first.

There were periods of multiple weeks - up to a month or so IIRC - where even my weight trending app thought I was gaining or maintaining, when I was pretty sure I was actually losing. Eventually, the expected loss did show up suddenly. I can't imagine how confusing things would've been without the weight trending app, i.e., if I were just looking at individual daily weigh-ins.

I'm pretty calm about weight management in general, kind of think of it as a fun, productive science fair project for grown-ups. If a person were more anxious or impatient about it, I think it could be more stressful or difficult to do.

I'd do it again, though, if I only had a small amount to lose.