The inefficiency of texting isn't really about the time it takes to type (though no one types as fast as they speak, and there's the delay in response), but the time it takes to have a simple two way conversation. For example...
Angela (A): Hey you, how are you? Do you want to do something this weekend?
Theresa (T): Hi, I'm ok, you? Hmm maybe, what are you thinking of?
A: Dunno; we could go out for a drink. I could do with one, that rusky is doing my head in.
T: Ahh, not sure about a drink, or even a pub. I'm meant to do be doing dry January. It's soooo boring. I don't think I can even set foot inside a pub, as the aperol spritz will be calling me, ha ha. Sorry about the rusky. You know what I've suggested you do with him, teehee.
A: Yeah, sorry about dry Jan, I forgot.
T: Well, we could go for a walk. Though it is a bit muddy out there. Do you mind it being muddy? I could bring the dog; and maybe the kids too. They could all do with a bit of exercise. Won't bring the old man though, he's such a misery.
A: Alas I don't have any wellies an the moment. Went for a walk a couple of weeks ago with all that rain. Remember all the rain, and floods? Was having fun skipping through flood waters when I found I had a titanic size gash in the side of my welly.
T: Oh no, that's annoying. Are they old?
A: Yeah, had them about a year.
T: Well you'll need to get new ones, you can't do without wellies around here. When are you getting some?
A: Well, it might take a while. I want Hunters, but I'm not paying 200 bloody quid for them! So I've been browsing ebay, and am waiting for the holy grail; an immaculate pair of 'never worns' for 25 quid! ha ha.
T: You could be waiting a while.
A: Yeah.
T: Look sod it. Let's just go to the pub. Sod dry January. Sod the kids, and the old man. And the dog too. Actually, maybe the dog can come, I like him.
A: Woohoo! Right, when shall we go? And which pub?
T: OK, looking at the diary, can't do Saturday until late as kids have shit on all day...............
So, this conversation for example could take at least 12, or even 24 hours back and forth by text between two busy ladies. However the same conversation on an actual call would take about 2 minutes!