That is true for a small subset of the stuff quants do. For a lot of other stuff an hour this way or that makes hardly any difference at all. A normal day for one of my quant friends basically looks like, get into the office and spend the morning putting together some calculations, run them and got to lunch, get back from lunch and discuss the results with some colleagues, if you decided to trade based on the numbers, call a broker. Seconds and minutes are totally irrelevant to her.