I dont think there is any real way to know for certain if it will be held against a candidate. But the reality of the profession is that it will likely be held against them as a lawyer.I completely get what you are saying but this depends on the firm you are at. My cousin is graduate recruitment at a magic circle firm so I’m fortunate I have a bit more transparency on TC recruitment.
I am currently on a competitive graduate scheme at a bank so I understand the pressures of meeting deadlines and expectations etc. The AC for my graduate scheme I asked for extra time and I still got a place.
Additionally I did a vacation scheme / internship via 10k black and able interns. I also asked for extra time and I got wait listed for the TC and there were other people who actually got offers that asked for extra time.
I think it’s firm dependent so I guess because I’m in a decent position I can be picky and will only go for firms that won’t hold extra time in an AC against a candidate.
In your case, it may be that you were an all around exceptional candidate too. Most people arent, and just need to hustle until they get an offer. Needing 25% extra time to do the work would very much work against most people.