I think my top has been 400eps in one week.
and top finished series in a month is 31.
i call the first thing a lie. a week has 7(days)*24(hours)*60(minutes)= 10080 minutes. assuming one episode has around 25 minutes. 10080/25 = 403.2 episodes. so you could watch around 400 episodes in a week if you won't sleep, eat, go to bed or do anything else.
assuming an episode has 20 minutes (skipping OP/ED+preview) you would need 400*20 = 8000 minutes. that would leave you with 10080-8000 = 2080 minutes = 34.66 hours sleep or other things you could do. that would be 34/7 ~5 hours for other things a day.
hardly believable, since the bottom case is too favorable. you need more than just 20 minutes for an episode. you could also just cheat and watch series where the episode are a lot less long then 25 mins. but that doesn't count.
second case is possible when assuming those series had 12 episodes, that would just take 9300 minutes or assuming 25 episode per series are 18600 minutes. while a month has 43800 minutes.
about the 1st case, it was hot summer and I had vaction

I did skip op, ed and recap. I woke up and started and went to sleep when I stopped. Also, I happened to watch 1st 300eps of One Piece and Gundam SEED & SEED Destiny. Both having re-caps, and in case of OP, skipping OP/ED/Re-cap/Preview meant taking off 7-10mins of the ep. And the avarage lenght for Gundam ep's is ~24min-5min(19min) and for OP ~22min, the lenght of recap was variable, longest being 4½min. + I skipped 2 eps of Gundam because the were re-cap eps.
and 3 eps of One Piece being fillers. so, it would be more accurate to say, I watched 395eps during that week.
I ate at the computer and used toilet about twice per day.
on the 2nd case, I had a bt of slump, and skipped school alot, the series were 12-26eps per series, ofcourse, I often skipped op/ed and always skipped recap/previews, taking off~5min of each ep.
and in case of recap episodes, it was about 1 per series. During this month, I pulled multiple allnighters.
7(days)*24(hours)*60(minutes)= 10080 minutes
(300-3)*(22min-5min) + (100-2)*(24min-5min)=
297*17min + 98*19min=
5049min + 1862min = 6911min 10080min - 6911min = 3169min = 53,82 hours of sleep & other things.