Is it common to see an active duty Army officer serve for 5 years, and only be a 2LT upon separation?

A few thoughts/comments:
- The short answer is that No, it is not common to see an active duty Army officer serve for five years and only be a 2LT upon separation.
- The pin on/promotion point for active duty officers varies over the years based upon several different factors (number of annual accessions, number of separations, whether Army is growing or shrinking, etc).
- The average or rule of thumb over the past couple decades has been about two years for promotion from 2LT to 1LT and about two more years (four years active service) for promotion from 1LT to CPT. Some times less time and some times more time based upon the factors mentioned in bullet one.
- In my 24 years of service I have never seen an officer separate after five years and still be a 2LT.

GySgt Bryan A. McGown "Gunny" No ... Unless he/she had prior military service before becoming a 2LT.

According to the Army Portal: Requirements for promotion from 2LT to 1LT - " Must have 18 months TIG as a 2nd Lieutenant (hence 18 months TIS as well). Almost 100 percent of officers meeting TIS/TIG requirements will be promoted to First Lieutenant."

From commissioning source to MOSQ there is a space in time. If you get hung up in that space in time, you cannot be promoted. I knew a WO1 that left WOCS at Ft. Rucker and was involved in a car accident en route to WOBC. He was severely injured and hospitalized for an extended duration. While undergoing rehabilitation, he was unable to attend WOBC and therefore, at the 2 year mark, was not promoted to CW2.
It is conceivable that this 2LT did not complete his OBC or was a problem child and was overlooked. Most likely a combination of the two.
If you have both your degree and completed your military education, the only thing preventing you from getting promoted is a signature from your boss. After a few strikes, you're out.