OP - I undestand what you are trying to say, but you fail to realise that what you would enjoy, other people would hate.
If you, your mum, your gran all work, does that mean you understand that other people have limited spare time on weekends? If that's when you have to do your cleaning, shopping, DIY, gardening, run errands, sort anything that needs doing and fit in DCs parties, clubs etc then weekends can easily be completely booked up. If you just drop round for 45 minutes for a cuppa, that's 45 minutes they have lost that they may have planned to do something else in.
Also in my experience, the sort of people who pop, tend to expect you to say "come in" and do actually give up the half hour.
I would rather be able to give guests attention, so I want to know they are coming. For someone to come over and have to be ignored because I'm busy seems rude. I was raised to entertain guests, not just say "help yourself to a brew if you want one" that seems so really horrible to me.
Calling/texting first means you can be certain the person you are popping in on actually has the time and wants to see you. Just popping assumes you think that at all times, spending time with you is the more important than anything else that person could have to do.
My home is not community space, it's my private home. I don't live with extended family, I don't want to. I would always call/text first, even if it's a "we're 10 minutes away at XXX, can we pop round on the way past?"