If you are preparing for a marathon, you will be running between 2 hours and 2:30 hours, depending on your profile. If you are already used to 2-hour long runs and want to do a little more, you can extend the duration of the long runs by 15 to 20 minutes if you think it will help you to do a little more.
For example, if you are preparing for a half marathon and want to run a little more at the weekend, you can also add 15 to 20 minutes if you are used to long runs.
For an ultra trail, you have a maximum of 6 hours available in the app. When exploring races (e.g. a Tour du Mont-Blanc in 3 or 4 days on the UTMB), you may be able to do more.
The risk of training too long is that you will be too tired in the following days or that you will injure yourself if you feel pain. Just listen to how you feel.
If you're arriving within 2 weeks of the race, we definitely advise you not to overdo it so you arrive as fresh as possible.