When to spread to multiple hands?

First of all, this question is based from Don S. statements in BJA that it is better to play one hand whenever you are playing heads up and spread to two hands (each 76% of one hand bet) whenever anyone else is at the table.

Assuming other players are at the table, do players spread to two hands at all times or just at high counts?

For example, say you are playing single deck, and if you were alone you would be spreding $20-$80, ramping from $20 to $40 to $80 at TC of 1, 2, and 3 respectively. If you were never alone at the table would you always play two hands of $15, $30, and $60 each or just spread to two hands at high counts?

I am wondering not just theoretically but in actuality, considering added heat from changing from one hand to multiple hands of big bets, and increasing your spread from 1-4 to 1-6 (assuming you only bet multiple hands at high counts).

Thanks