How does an E6 have 6 service stripes?

simple FYI some MOS's do not promote as quickly as others, take that into consideration.

That is not uncommon depending on your MOS you can either fast track or be an E6 your whole career. As a 19D (Cavalry Scout) I was promoted as soon as eligible....

A SSG at my unit just retired with 30 years of service, I have no idea if this NCO was ever in trouble or not. But it's not abnormal

I retired as an E6 with 9 service stripes. Spent my whole career in the National Guard and I was quite happy staying E6.

There are a great many factors to consider, here are a few.
1st is MOS. Is he in an MOS that is overstaffed and hard to find an E-7 slot? or a unit that really does not promote.
2nd is he prior service? he may have had a break in service as I did, I left as an SGT came back in 6 years later as an PFC and took me 3 yrs to get to SGT again.
he has a great amount of deployment stripes, it's difficult to get into NCOES while deployed.
He could be doing duty as an instructor of some kind, since he is the only one standing without what appears to be a diploma.
I have to ask if this is an innocent question, as a PFC you should be focused on your own career and not that of an NCO that you know nothing about.

If he is like me, I served 11+ yrs in the Select Reserves and another 18+ yrs on Active Duty back to back no gaps. That gives me seven service stripes(1stripe=4yrs) for a total of 30+ yrs in the Navy.

Not to hard to explaine in one way. I was in for 6 years got out as an E6,Came back 2 Years Later as SP 4 with 2 Service strips and a Combat Patch on Right Sleeve.( BIG RED ONE) Wasn't many of us around LOL

SSG second award. LOL

It's actually 4 years for each service stripe which means but if he got in trouble which may have happened he may have got knocked down in rank or his rate or MOS was hard to advance in,I was in the navy for 10 years and it was hard to make rank when a job is closed up so you may pass the advancement exam but not advance in rank

I had 3 years in the USAR before going active did 20 so I had 7 service stripes as an E-6 it son do not get bent. I worked with a SGT that did 12 years in the guard so when he was active duty 6 years he already had 6 service stripes