When someone makes E-5 (Sgt) can that person request a different unit due to the fact they were a SPC prior with the same unit?

I went from PVT to SGT in the same Btry, same Section. Yes it was a challenge, but one I would not change. I learned, and had to deal with difficult situations immediately. Your friends will support you, your buddies will make them selves known right away. To this day I'm still in contact with my friends from that time.

You can request all you want. That and a token will get you on the subway. I was promoted to E-5 in the same unit I was an E-4 in. There was an adjustment period for me and my Soldiers, but other than that I never had any issues with it. Be professional and adapt to the new role and you will be fine.

SPC (Join to see) Why do you want to leave? You can if you want, but why? Some units I have been in, made that SOP. But, I don't see a need. I went from E-1 to E-5(P) in the same unit and all was OK. Not always easy, but OK. It was probably better, as I had to learn to deal with Soldiers who were my buddies, and now were in my section, team, squad... It was very good experience. Why do you want to pop smoke?

The nco should be moved to a new squad, just to make a little easy his transition and to maximize his developing leadership skills

Request? Sure..Is the command obligated? NO

Its often cited as a best practice, but reality is, many times it does not happen for a verity of reasons..
Assuming the SM is a quality soldier, the commander is apt not to want to get rid of them.

The action is commonly done through a like MOS/ rank swap unit internal.....that means a leader in another unit is being torn from his squad. Or the Sm is sent to a unit with a vacancy, meaning the loosing commander is just loosing a leader.. Company grade CDR's are not apt to to that on their own..
the unit CSM managers team leaders (E5)
As the BN CSM has the WHOLE unit health under their preview and responsibility, the BN leadership is more likely to direct a new E5 move then the company level.

if your platoon is over strength in SGT's then you can

That is an interesting question. I have no answer for. I was always in a slot at least one grade above my current grade. As an E3 I was doing the job of an E4, I was in charge of the tools and equipment in our shop as well as the other men when ever the shop/Squad leader and his asst. Squad leader were both absent. which was not unusual . When I made E4 I was moved to an E5 slot till an E5 transferred in . Then I was transferred to another shop ,and put in charge of it An E6 slot. all tho on paper there was an E6 in that slot. He had no idea of/ nor interest in the job, so He had me take charge of the shop, and went back to the shop he preferred to work in. I very seldom saw him after that . I got my orders from my E8 or platoon leader.
When I reported to my new duty company was informed that there was no room for me in my MOS. I was asked if I would mind transferring to a different company. I accepted that offer.
I found out while in-processing that the Points had dropped while I was on leave. I was to be promoted as soon as orders were cut then they were back dated. The new duty company really didn't have a place for me either. I was asked to be the platoon clerk. I figured it beat being bored and just doing odd jobs. I accepted that job. Then I was told that it was an E6 slot since I was also considered the asst. platoon Sgt.
Reading back on this It seems that I was always in an unusual command situation.
Being in charge has always been natural. It started while in BCT as asst. squad leader then squad leader. I never had friends that I was afraid of giving orders to when necessary.
Reading this I wonder if this may be the reason I have no really close friends outside of my wife. I would not allow anyone to get really close since it seems like I would end up in charge of them at some point.

If possible as a company commander I at least would try to swap squads or platoons. I've experienced sometime when your spec 4 buddy becomes your SGT boss and, problems ensued. This lessens conflicts and allows professional and personnel development. However there were lots of times when this wasn't possible because of their job or not open positions.

I think staying and being successful is a testament to your leadership skills that will inevitably be put to the test. I didn't join the Army to make friends, I joined to do a job

You can request anything. Just be prepared to be told "no".