If a wizard with a warping score of 10 rolls for twilight time and wins the twilight time roll by one point they will spend 7 + stress die years in twilight. If the same wizard had won by 9 points they would spend one diameter in twilight. Since the roll twilight time is in part determined by a stress roll a wizard could in principle comprehend twilight's forever and still make it back, though it isn't very likely to happen.
regarding the point raised by saxonous, that warping and final twilight is the main source of "death" in the OoH. If memory serves me, it is explicitly stated to be so in several places in various sourcebooks. But in the linked thread about simulating aging of magi all of the people who had simulated the phenomenon agreed that in the rules as presented, it is not the case.
frostrose, the OP of the simulation thread, puts it like this:
As for my actual preliminary results, again I won't do a full breakdown, since it'd only get all revised in, oh, half an hour when I run the next simulation, but broadly speaking a maga can expect to live to about 172 (median 180), and the longest I can recall spotting off the top of my head was about 250. Furthermore she's overwhelmingly likely to die by having her decrepitude hit 5, which accounts for 70% of all deaths. The rest are more or less evenly split between aging crises and accident or violence, with virtually none due to entering Final Twilight.
This result surprised me, and I would not have been able to guess it. Sometimes however a numerical analysis of the data reveals surprising facts.