It would be good to have a little more time with the timed practice. With keyboard, spelling and accent challenges, even ten seconds more would be helpful.
The point of timed practice is to develop skills that one needs in actual conversation or in reading text at a reasonably normal speed. If too much time is allowed, then the exercise will not help to develop these skills. I do think that the amount of time allowed for a problem needs to be adjusted better to the length of the phrase or sentence in the problem, but on the whole, I think the amounts of time allotted are reasonable, and in some cases too generous.
I don't understand how these can possibly be completed in the time allowed. Even with constant typing (I can type almost as fast as I speak), using keyboard shortcuts, not putting accents, and knowing the answers to every question, I have not been able to come close to completing in the amount of time required. The timed exercises are completely demoralizing and need to be revised.
I would recommend that the amount of time vary per user. The system should use the amount of time you took to finish the first timed exercise to decide how long to make the second. Perhaps it can lower the allowed time after each interval to challenge participants without making them feel stupid for never being able to complete the exercise in time.