You arrive in Paris via a train station or an airport, you will need at least 35 to 45 minutes to reach the Grande Arche of La Défense with one or two changes to the metro and RER and once there you will have to reach your meeting place on foot and you just have to look at the map of the business district to realize that this solution is far from being the most practical to arrive serenely at an appointment - even if it remains the most economical.
You have chosen the taxi, you will gain in transport comfort and be dropped off directly at your meeting place but in addition to a possible wait in the queue of taxis, you will have to deal with Parisian traffic which often turns out to be nightmarish during rush hour, removing your control of time and your budget.
The usual time of around thirty minutes to connect Roissy-Charles-de-Gaulle airport to La Défense and vice versa can thus double or even triple.
Reaching the main Parisian stations takes, outside peak hours and traffic hazards, on average 25 minutes and can go to 50 minutes without you being able to control them.