I have not explicitly written any logic for variable commas ...only just the fact that there should be a lil bit of time gap between the commas. Just so that I can understand your question better...why does it matter ..like that's the way that has been pasted in the text so...the interface is showing just that.
beardyw|3 days ago
"It arrived, as if by magic" should be read with a significant pause, whereas
"It contained potatoes, cabbages, cheese and beer" needs no pause at all. The commas merely indicate a list.