Asking your advice how to deal with people responding later than they said they would

[questionzzz]

In the past week I've had two similar incidents with two different women in two different workplaces which caused me a huge amount of stress and anxiety. Both these women are in that blurry friend/colleague category (one of them I know for 10 yrs!). They were both supposed to prepare and send me important documents for different projects where a fair amount of money and work was involved (eg, draft budgets, evaluation forms), and they did- but later than they said they would. Eg, one of them said she would send it Sunday evening, didn't get it till Wed 11pm (along with a huge rant about how busy she is, how many commitments she has etc etc).

Anyway, the point is, neither of them have done anything wrong, they were supposed to send me something by a certain date (which they knew and had been discussed), but they just sent it later (but still in time to meet deadlines)- and after a fair amount of "follow up" and "friendly reminders" from me.

During the period where they said they said they would send it, to when they actually did, I was getting so stressed out and anxious- it was constantly preying on my mind, obsessively checking social media, basically making myself sick. I did mildly point out that I was surprised it was taking so long and they're both usually pretty good at responding- long rant again. I was actually thinking in the time she was taking to rant at me about how busy she was, she could have actually finished the piece of work I was waiting for.

Because it is happening twice in one week, with two different woman, about two different things, I am thinking this is probably the new "zeitgeist", people are overworked, stressed out, rushing to meet deadlines, taking on more commitments than they should.. and I need to "chill". Basically I need to change the way I approach and think about people and their work, before I collapse from anxiety, for my own mental health.

How can I accept that this is just the way people are working now, at least in my own little sector, and become calmer about people taking longer to do what they said they would do? Do you have any experiences about this?

Give them an earlier deadline so that they can still be late and you will still be on time??

That's also the way I'd handle it. But I would wonder if the 'friend/colleague' line had become too blurred.
I don't think they should rant at you about how busy they are, a deadline is a deadline.

‘If I do not hear from you by [deadline] I will [action they most likely don’t want you to do].’

For example: if I do not hear from you by close of business on Thursday, I will submit the document in the existing format.

Then follow through (including your ‘deadline’ email and a note saying [colleague] was consulted and didn’t have any comments/input).

Honestly, I think ranting is a bit unprofessional. If you’re going to be late, you should let the person waiting on you know you’ll be delayed and give a new timescale.