Spin can cause damage basically in three ways.

1) Fabrics sensitive to wrinkling can be affected by the crushing effect, in some cases permanent-set wrinkles or creases. Both spin speed and time can be factors.

2) Fabric can be pulled through the drum perforations and catch small tears from the sharp edges of the holes. Spin speed, size and design of the basket perfs are factors.

3) Stretching can be a cause, primarily on frontloaders and non-agitator toploaders if an item spans across the drum.

Are longer spin times detrimental? Mostly, no but sometimes can be in the ways that Dadoes listed. Cotton bedsheets made in the last decade seem prone to creasing. Have you seen the on-going thread on deep creases in bed sheets?

Honestly, I’m your case it might cause more wear. That is only because you don’t dry them. However, for my family it likely is very beneficial since they will spend less time in the dryer. I wouldn’t say the time is as much of an issue as the spin speed itself.