Dear Sara,
I have taken 3 of my pages using Dimension as well as Segment. Below are the results for your understanding :
By Segment: Have created a segment for those three pages by 'HIT' container. Below is the screen grab i got:

When i added Custom Link as a secondary dimension, the result for zero.
By Dimension: Have selected the pages manually as a dimension. Below is the screen grab i got:

When i added custom link, i can see few line items with its own Total Seconds Spent.
Example : I loaded the page and didn't navigate anywhere for 30 Sec, but clicked on my chat button where i am capturing Page Name in Custom Call and exited. Since Time Spent is calculated based on the Line Item at the Server Call, Dimension will have Total Seconds Spent = 30. When you apply 'HIT' segment, the Custom Call will not be accounted and thus the visit is considered Bounce with Total Seconds Spent = 0 / Not Calculated.
Conclusion:
Dimension will add the Total Seconds Spent on s.tl() calls like Custom, Downloads and Exits.
But when you create segment by 'HIT', it only consider the s.t() calls i.e. will not include the Total Seconds Spent on s.tl() calls like Custom, Downloads and Exits.
Its your decision to take the needed based on your business requirement.
Hope this helps.
Thank You
Arun