Yes, I have heard that phrase - lots of white space - but I absolutely dispute the idea that it is 'the convention' to write each action on a separate line. I keep my action lines to 3-4 maximum but those paras may contain a number of individual actions.
At random, here is an action paragraph from Ordinary People:
'Conrad with goggles ready to jump. Swimming training session. Conrad and six others dive. They swim in their lanes.'
'Beth goes upstairs with her shopping. She knocks on Conrad's door. No answer. She enters in an authoritarian way, then comes out and closes the door. She then goes to the next door on the landing (Buck's bedroom) Stops in front of it, hesitates then enters.
There is no confusion here, in the same way as I don't believe that putting the series of actions that I did in one paragraph was confusing.
Jed drops litter. Jed notices his phone. Jed answers his phone - by answers, certainly here in Britain people would take that to mean he picks it up and presses the button to connect to the caller. As I said, it doesn't matter to me exactly what happens on the other end of the phone. We don't see it. We don't hear it. All we witness is Jed's reaction. That's what is on screen. That's all I wrote.
Jed answers the phone. His expression changes from one of hopefulness to anger. How much more do you need? Really?
Yay, got it in one, Pops = yes, you understood at the first attempt, grandfather.
I think we may just have to beg to differ over these points!
I just have to accept that you don't like my style.
Leo says 'I suppose there's very little I can do in the circumstances' followed by 'except perhaps? ...no it seems scarcely possible.' Jed interjects, after the first phrase 'Yay, got it in one, Pops.' I fail to see why this is so unclear unless it is something to do with my British propensity for understatement and sub-text which may not suit your tastes.
Again, I hate 'on the nose' dialogue with no subtext and I trust my readers. I think it insults their intelligence to spell everything out word for word. If that loses me some of my potential audience then I have to accept that. It's a choice I am living with not to dumb down and sell out!
Regarding the short scene you cite - when I say Jed sees the mobile phone flashing on the seat, this is a way of conveying camera directions without stating them which is something directors abhor. Jed drops the litter then sees the mobile which = the camera shot is from Jed's POV looking at the phone.
I didn't put in how Jed answers the phone, crediting my actor with the improvisational skill to muster something. In fact, I had it in mind that the person on the other end might launch in to a vituperative onslaught so Jed would not say anything. To me it doesn't matter, or forward the story, that he says Hello or doesn't. It's immaterial and would be totally 'on the nose' which I try to avoid. The only important thing is that the call upsets him. It seems very obvious from his response that it's some girl and what she says makes him angry. It doesn't matter what. I don't wish to spoon feed or constrain by being so utterly prescriptive when it doesn't matter.
Happy - to address points one by one so if they disappear I won't lose everything...
(I appreciate that you take the time even if I don't always agree with what you say!)
Regarding breaking up my paras - I can see that this might help with clarity and am sure it's the convention with narrative writing to contain one image/ action into one para HOWEVER I'm not sure the same applies in screenwriting or each screenplay would be about a thousand pages long and consisting entirely of single lines.
I generally adopt a telegrammatic style for screenplays and this hasn't presented a problem for the people who have produced five of my scripts.