They can’t increase the block rate to get 10% more unless they also have > 50% and privately mine for 212 periods to reliably keep the MTP held back. Publicly they’d need something like 99%. But if they do a private mine they get 50% more blocks per time than they would publicly after the 1st adjustment for as long as they mine.
But they don’t get the 10% gain for the same reason. Delaying 600 s in 1st cycle lowers the difficulty enough for him to get an extra block in the 2nd. But getting 1 more block means difficulty goes up in the 3rd cycle to offset the gain if he doesn’t do the -600 in the next cycle. So he can only maintain getting 1 extra block per cycle. It’s not an advantage that can accumulate. So he gets only 212 blocks which isnt important compared to getting 212 × 2016 excess blocks from doing the private mine (over a public mine). So it’s a 0.05% gain over a private mine and a -3 hour limit is a 0.9% gain.
- cycle => blocks/cycle at 50% => blocks per 2 weeks
- 1 => 1008 (normal before attack) => 1008
- 2 => 2016 (private mine begin -3 hr timestamp) => 1008 (takes 4 weeks)
- 3=> 2016 (-3 hr) => took 2 weeks minus 3 hr due to previous stamp
- 4 => 2016 (-3 hr) => took 2 weeks minus 3 hr
He keeps the last timestamp in a cycle at current time. There’s not a way to hold it back or push it forward to help. The only thing he gets over a private mine is more time at the end to mine 1 extra week than he otherwise could have. After 112 cycles he would get a gain of 2 weeks to get 2016 +18 blocks more blocks than doing nothing, less than 2% of the “excess” gains of just being a private mine ( 2016/2 * 112).
I see no reason to dismiss the concerns that -600 will break something. This is my 3rd request that someone explain how it helps.