Based on what I saw, I'd estimate Bitmain was replaceing S5's with S7s for 2 months at most, and possibly with S5+ for a month or two before that (and then likely sold those S5+ as "new" units once they got the S7 into production).
I don't believe for a microsecond that the S7 has been in production for 6+ months.
When you say what you saw what are you referring to? Did you get to see a plant? Just hashing online? What specifically?
"Used" S5 sale.
Hashrate fairly stable for the first part of that.
ETC.
If the S7 had been in production for 6+ months, there would have been a much longer and bigger hashrate bump due to Bitmain using them internally.
It is hard to write the reasons i have for believing the top builders manage the rate of growth. but here g
It would be counterproductive for "the top builders" to manage the rate of growth, they'd be eating THEIR OWN PROFITS to do so.
Consider "market share" and how effective it can be in the long term to dominate market share.
Additionally, there are limits to how much gear any builder CAN build, none of them have huge financial resources.
The REAL reasons for slower growth rate of late are
(1) the bitcoin price collapse, giving much less incentive to folks to mine and lower profits for those that DO mine and sellers of mining gear
(2) the tech race is slowing a TON as the tech used to mine Bitcoin gets close to the best AVAILABLE tech
(3) the COST of developing new tech gets a LOT higher as you get close to the "bleeding edge" on tech
(4) the death of some miner companies due to the above factors making them unprofitable
There is ZERO "economic need" to pace growth rate, in fact there is at least one good reason to NOT pace growth (ref market share) for any single company, and there have been way too many cases in history where it's hasn't happened even where it was a GOOD IDEA to do so (look at the history of Oil Production for a well-documented example).
Do keep in mind that there is a significant random factor in hashrates.