Now this maybe a rant, but, stop trying to make every historical tv series feel like GoT. The formula just doesn't always work nor does the style of narration.
As for my personal opinion, the first three seasons of the Vikings series was really enthralling and interesting to watch. But the later seasons of 4 and 5 do not seem to live up to the expectations that were build up in the earlier ones.
The style of narration changes in season 4 and really grinds up in 5 however, when Ragnar, Ecbert and Rollo are pushed to background and the main arc now revolves around the petty squables of Ragnar's sons, Lagertha, Aethelred and Floki (who till then was very respectable).
Focus shifts, from the interaction of characters who want to achieve some goals and how they plan on it, to the individual characters and their feelings and emotions. It's no longer about what happened as a whole but more about what everyone is doing and thinking about something or other all the time.
I really don't care what each character thinks about one another and am not interested in watching them have sex. Elaborated monologues of Floki in Iceland, hyping up Ivar's image as a tyrant, giving too much importance to side characters who rarely add any importance to the story and simply wasting shots focussing on their facial expressions are some of the biggest downsides of season 4 and 5.
I really think the story narrated in 20 episodes can be cut short to 10. It is possible when half of the episode just consists of close-up shots of main characters and how they change their facial expressions. Atleast, we keep our hopes alive for S6.