How does an E6 have 6 service stripes?

There are a number of reasons...some good and some bad. MOS realignments, promotion freezes (point system) DA board promotion number, possible UCMJ issues. Because you're new to the military and not aware of the Army system back in the days it would seem 'strange and confused' but during the '90s and Y2k, the Army made MANY changes which greatly affected promotions thru-out the ranks in which some MOS promoted rapidly while others were at a standstill for a very long time...

Maybe not as common these days. I served with a 45yo Specialist who had 10 years in back in 2006. Stop loss was a bitch for some dudes who couldn't make rank.
I did a funeral for a Navy vet who retired as an E5 with something like 27 years in. Before the aspects of High-Year-Tenure came around, I guess it wasn't uncommon to see guys with loads of time, but not a lot of rank back in the day.

I'm not sure if I've answered this one already, but there are a number of reasons that a career soldier with 18 years or more is a Staff Sergeant and NOT a Sergeant First Class or senior. One of the ones that I've seen frequently in the Support and Service & Support world is promotion points staying at 798 FOREVER. There's also the situation with an oversaturation of junior soldiers that got their stripes all at once. One of the other ones I've seen is schools holding up the promotion process i.e. you have to graduate the school at YOUR INDIVIDUAL LEVEL plus complete your Structured Self-Development Courses for your level BEFORE you can be placed on the promotion list. That can cause a huge backlog of Sergeants waiting to become Staff Sergeants, which will delay their 1st and 2nd looks later on down the line. On the flipside, there are Sergeants First Class with 8 years and a few months in service as well. I've seen all kinds of craziness with rank and promotions during my Army career.

I’ve seen this type of conversation for years more then 5 years to be more exact

I retired as an E-6 w/22 years.... admittedly though... I had a nasty habit of running off at the mouth when I was a young Joe... that being said... I have 5 friends who also retired within that same time frame.... couple years less actually but none of them had a big mouth like me and still only hit staff before retiring.... just say’n

I was in the Military for 23 yrs never had a article-15 or any type of bad marks of any kind but I was hurt while in PNCOC an could not advance in rank an was forced out of active duty with a medical discharge was transferred to the Kentucky National Guard without a break in service an retired their.

As the Chief was saying must be in a slow rank structure. I was in one myself. 91c is a utilities repairer. They are in the same group as mechanics and couple other classified groups. I started in infantry my 1st 6 years to go out with an SSG rank. I was out for 22 years got back in as SSG but if I’d stayed infantry would have probably made master SGT but the field I came back in very slow moving up cause I was also a federal tech with all of us mechanics, ultiites repairer and couple other. We had just in our group that fell in line at least 300 on that post and many others that was normal civilians that was in our group in one location

I am a SSG with 6 service stripes.....come at me bro!!!

Please understand that in everyone situation things are different explanations, I retired in 2015 with 25 years of Military Service completed and documented as an E-5 Sergeant, 17 years time in grade; with no Article 15 with 1 ARCOM and 5 Army Achievement Medals. I don't know the Staff Sergeants situation but it is possible. In 1975 I knew of a Col. that was in the big rift after Vietnam and he was reduced from COL. to SP/4. I won't go into details of situation because it is Militarily Sensitive and I have been warned by JAG. It is possible as you have seen.

Cutoff scores have a lot to with promotions, in order for me to Make Sergeant and Staff, the cutoff scores were at 999, when I was active duty, there was only one SFC slot open, with 105 people hoping for that slot. Each branch has different requirements towards promotions. I have seen senior SSG's turn down SFC as they have plans on getting out after 20yrs. I love it when a Pfc is an expect at something and has no idea on what's going on.