It seems this is a tactic/technique requiring well-drilled, well-disciplined troops. My understanding is that most of the men who went a-viking were not professional soldiers and did not typically fight in well-drilled formations.
Keep in mind that The Last Kingdom doesn't actually depict víkingar, but rather an invasion by an actual army. Víkingar would not have been, on the whole, terrifically disciplined, but then again they didn't need to be, since their modus operandi was, basically, "show up, steal everything that's not rooted to the earth, kill anyone who gives us any grief, then take off as quick as possible." The Danish Invasion, on the other hand, was an invasion undertaken by powerful individual actors banding together under a single command structure. It was an army, and to that end, they fought like an army - formations, orders, etc.
You can take a look at Paddy Griffith's (poorly named) The Viking Art of War for an idea as to how Scandinavian armies worked at that time, but it wasn't too far off from any other early medieval infantry-based army.
Not the original replier (obviously) but I think the answer to this question:
Will perhaps answer yours as well.