First of all, thanks for answering Nick. Despite my respect for your level of experience and seniority, I don't agree on all points.
Imagine counting massive amounts of wagered chips, only to have all players fold? It would take too much time.
I teach my students to start counting when a player contemplates a call/raise, if and when the player decides to muck his cards while you are in the process of counting, leave the counting for what it is and move on with the game. Therefor there is no time loss, you can only gain time in my opinion.
I have no objection when a dealer announces an obvious bet amount.
It feels strange/wrong to me to handle a bet/raise differently based on its obviousness. Not only does it go against my believes that all players (and with it their bets/raises/calls) should be handled equally, but it would also encourage players to make unclear bets and gather massive amounts of chips with a small denomination.
The actual discussion here goes as follows:
Some of my colleagues say that it is "absolutely not done" to touch a players all-in bet until his opponent asks for a count. The reason they give for that sounds very strange to me but maybe it makes sense to you.
They say that when a players shoves all-in, the opponent might read "around 10k", what would be a reason to fold.
But when the dealer starts counting, it turns out to be 6,9k what would be a reason to call.
In my opinion there are two different approaches to this.
From the players perspective, of course he should ask the dealer for a count, he is responsible for his own game.
From the casino/dealers perspective, why should we cooperate in this smoke and mirrors game? Just state the bet amount, regardless its obviousness. (Only when the player is contemplating a raise/call of course)