Is it true that I should post on Instagram early in the morning and/or late in the evening?

I have heard, that posting on Instagram should take place within those hours, because people usually watch their threads when they are out of work (or studies). I post too much, and I haven't noticed a difference, to be honest. Do you think it works?

11am-1pm but mostly between 7-pm-9pm

I believe after 5 pm is best. Until 9, people should interact (after most people's working hours). Overnight, you will also get some followers and likes due to people in different time zones. Also, if you're into a niche that appeals to a younger generation like cartoons, and fanart, after 3 pm is good too cuz that's when school ends. Morning's quite nice too as people will check their feed before work or school

Depending on your audience, schedule your posts. Adults, probably 5PM to 7PM would be a great time.
And as a side note, one quality post is better than 5 "not so bad" posts.

The best thing you can do is to test it.
Create an excel sheet and try to post each day at a different time. Then write down the engagement/likes/views etc. in the excel spreadsheet and after enough tests you can determine which hour is the best to post your picture/video.

Ever heard the saying "it's 5 o'clock somewhere around the world?" It's true. Not all of our followers are in one neat little place close to your time zone. You'll need to test and see what gets better results. Do it for about 10 days, posting at different times each day. After 1 week you'll start seeing a correlation to where your fans are located and what works best. The 3 extra testing days are to just make sure.

I'm not sure that's true. Experts say that posting that way might boost your likes, but I haven't seen that much progress. Although some photos do perform better if you post them half an hour before work - 7:30 or 8 am. But it worked just a couple of times.

I again don't think its worth it to do this unless you want to hit the explore page and you know 90% of your followers are up at a certain time.
My followers are world-wide and I don't see total engagement until 24 hours has passed. Only then will I see a solid 6% engagement through likes alone.

On ny page i usally post in the morning. Ppl tend to be on their phones early morming

It depends on the user's time zones! but mostly those hours are when the majority of users are connected!

In EST USA, we post on Fb at 1130am and Ig at 330pm. Across all the accounts we manage, use picks up dramatically at 1130am, dips slightly after lunch, picks back up at 330pm, up dramatically at 630pm and cruises steady until 1030pm, starts dropping and is dead at 1230am. These are regional SMB accounts, mostly wanting to attract day workers to a brick and mortar.

NOT AT ALL, IG algorithm have change this... this is old.

Best time to post is whenever you want to, Keep in mind algorithm is not chronological it's by engagement.

The time of the post is not related to the viralization of the post, you can use as a reference IG statistic that tells you when most of your followers are active but that doesn't mean much.

I have done different test and realized that there is no correlation between time of the post and viralization.