While Venan is correct to say that theoretically there is no need to burn a single gs for gold timing (2h 20mins), what you need is really max attendance of 40 from start, with raiders staying till the end (i.e. returning to dump energy when full or close to full). Approximately, 2hours 5mins and the raid will end (assuming no stamina elixir or energy enchant), based on my preliminary calculation of 2006 hits. So you get about 15mins of leeway for slack time

Theoretically nice?
In reality, good luck trying to find 40 raiders online punctually (this part is still doable really)...AND staying for 2hours ++ (this part is hard...how can one ever predict all 40 raiders that joinwill be able to commit their time so strictly? real life ALWAYS crops up for people. In a team of 40, I bet at least a handful will have work/family/kids/gf/bf/parents/boss/accidents occuring in that 2hours).
Hence reality is that GS burning is ALWAYS needed to get gold timing. In the past, high attendance rate would be sufficient since there was no raid cap, less hits were needed (about 1400 hits), and the gold timing was longer at 3hours.
Venan is trying to make silver the new normal, OR they are trying to impress a point that gold timing are for gold-standard guilds (i.e. stellar attendance and robotic commitment levels) or gold shield-rich guilds lol.
I'm not disagreeing with the way Venan is making the difficulty level, but just wanted to give everyone a heads up of what to expect if you're gunning for gold (at least for VG). After all, they did improve the payout...so really, the new silver timing payout doesn't differ that much from the old (and arguably much easier) gold timing. And the new gold timing payout is REALLY sweet (hence you burn more gs for it).