@greghHW3PE
When using Revit Fill Regions in a detail family, be it linear or not, you can assign either model or drafting patterns.
- Model patterns will align with the rotation of the element but scale up and down according to the scale factor of the view.
- Drafting patterns will conserve the pattern spacing according to the view scale and, except for detail components and filled regions, allow three options for alignment.

So, in the case of a linear detail plywood element family, you would need to define a model pattern.
Considering the various scales at which your detail elements needs to be readable and how to ensure a proper reading at each, a possible workflow would be to define 3 groups of scales (<1:2, 1:5, and >1:5) and assign model patterns for each of the three view detail levels (fine, medium, low).
Your linear detail family would then have the filled region duplicated three times, assigned visibility to the view detail level and corresponding model pattern. When the detail level is changed in the view, the corresponding scaled model pattern will be displayed.
An added bonus would be to also adjust the line work for the three detail levels so the fine detail views will have a correspondingly bolder line than a low detail level view where the linework can become muddied by the close proximity of two sides of the plywood panel.
Additionally, when the fill pattern becomes to dense, revit will substitute a blank masking region, which is logical in that a 19mm thick plywood panel at scales of 1:20 and higher rarely benefit from a fill pattern.
Hope this helps,
-luc