This is series six and there is a progression. I think it helps to watch the earlier series to become familar with the format; several different characters whose lives have all been linked in some way in the past but it can take up to six episodes to figure out how. Some big names in those early ones.
I was irritated a tad with series five, neither Jesse nor Sunny on top form as both had personal problems plus Cassie left big shoes to fill, but I took to Jesse more once she and Sunny reset. For me, he is the consistent, steady, beating heart of the series.
Jesse has a different style to Cassie but I think it was important not to have a carbon copy. Also, I think her slightly abrasive style contrasts well with Sunny’s much quieter calmer approach.