First and foremost: it’s your hobby. No one is going to tell you how you have to build the models you bought.
That said, I -personally- think your examples are not in line with the intent of the game. Kings is a game that pits armies against each other. An army is a number of units with ranks and flanks and if there’s not enough soldiers in the unit, it’s not a unit.
In order to count as a “unit” that does have some measure of formation, the unit has to have a number of solders in there. The game suggests PMC which is 8 soldiers for a 10-men unit and 15 for a 20-men unit. I have been known to use slightly less than PMC, but I strive to build complete units. Personally, I would not use less than 7 soldiers in a troop, otherwise it wouldn’t be a cohesive unit.
If my terrain/unit base is so full that I cannot fit seven models on there, there’s too much terrain. Even so, with a bit of creativity, you can easily build ruins and fill them with units. See my ghouls for example:. In your case, remove the round bases from the models to gain more room. I think you can fit 15 deadzone human soldiers on that base if you move the front wall to exactly the border of the base and get them off the rounds.
Building an army from an ambush box is -I think- not possible. Depending on the ambush box, you can maybe get 500-ish points out of it, but little more.
For instance: the goblin ambush box is great. you get 40 goblins and 2 chariots/mincers. (edit: and eight mawpups)
using 15 goblins per regiment, you can build 2 units of sharpsticks. then, buid the 2 mincers as a mincer (monster) and king on chariot using 2 of the 10 leftover goblins. This leaves 8 goblins leftover for future projects. If you’re into converting, these rabble can be converted into luggits with a bit of spare plastics, so these final 8 goblins can become a luggit troop. On the goblin sprues, there’s also mawpups. The ambush box has 8 in total, which makes a great mawbeast pack.
Both the luggit troop and the mawbeast pack troop, as well as the two characters can be unlocked using the two regiments
This force counts 6 units and almost 600 points which is fair for an ambush set.
To conclude, multibasing is a great tool to create diorama’s. The added efficiency of the models in the collection is a nice benefit, but no goal in itself.