First, history lesson, I'm sure you don't want "style one"
We are currently on the 3rd edition of fox. The 1st edition is a FIXED SIZE fox that the most populous server can kill in 2 minutes while the vast majority of servers cannot even kill--there might be around 50 servers that can.

So what you want is probably version 2.0, not 1.0.

Second, on fox readjusting. During 2.0, the fox have a normalized period of 5-10 minute. This means that if it's killed under 5 min, the next time it will be buffed by 40-50%, if it took more than 10 min to kill, it will get nerfed by about 30%. There is every reason to believe that the current fox would be the same, except it seems that the time period have changed. Our server kills it at around 10-15 min, and it have not changed. So i would guess the new period is 10-20 min or something to that effect. So for the freshly merged one-shot server, it should grow. As for the server that took 35 min, it should shrink (note that taking 35 min would mean it ends at 8:55, not 8:45. While fox "start" at 8:10, the battle only start at 8:20)

Third, Masuri. The time window for masuri is EXCESSIVELY long A lot of people complain about masuri matchmaking not realizing that this excessive period contributes to the problem (longer overall time = smaller pool at any given time = larger gap between players in pool = bad match making). So frankly, anything that shrinks the masuri window is welcome. You only need 20-40 min for masuri, so as long as it's at least 1 hour long, it's fine.

Lastly, many people have asked for time extension from version 2.0. Because the bigger the normalized time, the bigger the fox and thus more damage which leads to more coin income. So whereas 35 min would be a bit excessive, since it runs the danger of not finishing, 10-20 or even 10-30 would be a welcome change to many.

Well, if you mean 2.0, the mods said they would self adjust, I think it was in the patch note too

and from experience in our own server, the time was 5-10 min as we've hit both ends. And it was also talked about and confirmed by mods. This came up quite a bit due to new server starting with a super weak fox which takes awhile to adjust up.

3.0... well.... that's just guesstimate.