There is a fine balance between the base and the model count, in my opinion. I’m not generally fond of using minimal model count, as the base tends to look spartan, and does not have a rank and file army feel to it. However, with some models, it’s nigh impossible to squeeze the minitures onto the required base they are assigned, (Frostfang Cavalry being a fine example). So, it is a case of finding a good balance. With some armies, where ‘rank and file’ is a loose concept, like Orcs or Zombies perhaps, and everyone is eager to get into battle, then you can cram them tightly together at the front of the base to reflect this, and leave space behind for the decoration of the base itself. You naturally wouldn’t see such reckless anarchy in a regiment of Dwarf or Roman legionaries, who would maintain discipline even while wading across a bog or through dense forestry. So the models and army need to be considered . However, for my personal preference, i do like a populated look in my bases rather than the look of 'straggling survivors of a nasty encounter, struggling home after the battle 'type .
This said, the more i create multibases, the more i get out of them, and the better at it i am getting, (IMHO) .
Although i tend to avoid a spartan model count, i also dont always concern myself to cram every single model required on the base, and can usually shave off one or two from a unit for use in Vanguard or to go towards another troop, without making the base look model shy.