How does an E6 have 6 service stripes?

I had over 30 years in the Navy (1977 to 1991) and in the Army National Guard (1992 to 2013). I retired as a SSG. So? You need to stay in your lane Cream Puff.

One reason may be he had a break in service.
Secondly, promotions don't come easily for some.
His rank and high service stripe count doesn't mean he isn't an outstanding nco.
His promotions politics could be weak.
I was that guy. I retired as a SSG. Some,my doing,some theirs.

He probably served a different branch before. Or he lost rank

The best 1SG I have had was a SPC for 10 years and made 1SG in 18. He didn't want to get promoted he liked that E4 life style until one day he decided it wasn't enough and he wanted more then he went out and got it.

I served with a man who exited the army as a SFC. He returned to service as an E5, and began the climb again. He had 6 or 7, and he was a great guy. He did look odd with all them service stripes though.

Uh I have one, let me see I retired as an SSG and that's 20 years. So maybe the answer is an obvious one and he's been in for at least 18

I went WO to prevent being a SSG for life - only 2 selected for E-7 in the 3 years prior to my selection for WO. Made E-7 and pinned the day before I left for Rucker - what a kick in the pants.

Beat you face

There are multiple possibilities. He could very well have not gotten promoted as quickly as others. He could have been demoted at some point or multiple points in his career. He may have taken an administrative reduction in rank for a specific position. Some NCOs never see a promotion to E-7.

I know it is hard in some MOSes to get E-7 and in a few it is hard to get get past E-5. I knew a lot of SSG that got out and a lot of SGT that got out as well my mos was hard to get SGT even after 8 years