Always always always set the time you have available if the previous weeks’ aren’t representative of what you have that day, whether less or more. The advice is always a function of available time and the assumption is that the pattern that you have used to establish your current training load is what will be maintained. That’s an assumption (if you think about it, it’s an entirely appropriate and essential assumption) but it is easily overridden by simply adjusting the time in the filter.
Look for the ability to do this more easily coming as a feature since many users don’t realiize that this is an important thing to do. If you have 2 hours to train and want to improve, train for 2 hours even it the recommendation is for a one hour workout. This is independant of your deficit.
Remember that the deficit helps you see how the principle of progressive overload needs to be applied to reach improvement goals but it isn’t a strict training recommendation where if your deficit is 10XSS you should jump on the bike and do 10XSS workout. You do what you can do if you have the time and the system presumes that what you did in the past applies at the moment. If that’s not true, change your available time. Simple as that and do more or less than the what your deficit is. You will catch up in a subsequent workout if it’s less than your deficit.