The longest winning streak.

[Trev]

I'd throw in a run of six for Symphony X from The Damnation Game up to Paradise Lost.

I'd personally add in one more with Iconoclast, but I know for a lot of people it was a bit too removed from their usual proggy leanings

[Bürggermeister]

The one you turned it off during just last week 

I felt I did well to get that far in the first place 

[leoos]

The Quietus did a lengthy piece on Slayer's 3 album run from Reign in Blood to Seasons in the Abyss recently
https://thequietus.com/opinion-and-essays/black-sky-thinking/slayer-best-albums/

[Mooncat]

I've always found Testament to be meh in general. Skolnick is by some margin the best lead player in thrash, but when your only enjoyment is "wait for the lead", it's a tough sell.

Skolnick is great but personally I'd have Friedman above him, I think his leads are more memorable. Could Hammett literally be the worst out of all his peers?

I think Testament certainly qualify for a good streak, with the only caveat being the quality of that streak in general is lower than something like the Sabbath streak.

[Black Shepherd Carnage]

I think Testament certainly qualify for a good streak, with the only caveat being the quality of that streak in general is lower than something like the Sabbath streak.

In a nutshell, yup.

[Mower Liberation Front]

I'd add Slough Feg, Blind Guardian, Rage and Sentenced to the list.

[Cailleach]

I am going to include Malokarpatan on this list- everything they have released is quality.  They just seem  to get better with every album too

[ochoill]

Devin Townsend's catalog is all over the place but depending on how you look at it (does SYL actually count as separate or not?) you get either six or nine albums in a row of top tier material.

Ocean Machine
Infinity
Physicist
Terria
Accelerated Evolution
Synchestra

City, SYL, and Alien all also released within those.

[ochoill]

There isn't a single bad Torche release either so that's five albums and two EPs in a row too.

[Carnage]

Has anyone mentioned Bolt Thrower yet? Not a dud in sight.

[Circlepit]

Type O Negative have to be on a list of when it comes to a streak.
For me they are one of those bands that when you want Type O, nothing else will hit the spot.
Hardcore, Death and Black Metal have desert island disc artists but there was only one Type O Negative.

[Black Shepherd Carnage]

Has anyone mentioned Bolt Thrower yet? Not a dud in sight.

Shit yeah, good call. 10? 8 albums + 2 EPs?     

[The Butcher]

Has anyone mentioned Bolt Thrower yet? Not a dud in sight.

I'm happy to lock that answer in.

[The Heretic]

ACDC - 5 in a row

Let There Be Rock (1977)
Powerage (1978)
Highway to Hell (1979)
Back in Black (1980)
For Those About to Rock We Salute You (1981)

[vinterland]

Dark Tranquillity's discography from Skydancer to Fiction, totalling six albums and two eps is fairly rock solid throughout. Marduk have hardly put out too many stinkers over the past 35 years.