Well the s9. had a lot of bad batches say 4 to 11 way back say. sept 2016.

It came out in April 2016. batches 1,2,3 were decent. Then a drop off.

but in feb 2017 on they got their shit together.  They put out a lot of s9's they worked for 2 years or more.

The s15 and t15 came and gone quick under a year
The s17 and t17 lasted a year- 14 months . say April 2019 to  June 2020

Now the s19 are out.

So no time spent on bettering the gear has been spent.

Also. I am willing to bet that. a ton of s17 gear was burnt due to too much over clock.

But that is another guess.