Hi,
Plant Guide tool have its own parameter to set the point count when planting a guide. Open the Maya Tool Settings to find the settings for the Plant Guide Tool when the tool is active. The parameter Point Count determines how many points the plant guide will have, this parameter is not procedural, meaning you cannot change the point count for ALL the planted guides.
The reason why you cannot change the point count of planted guides using the Point Count parameter in GuidesFromMesh is because those new guides are not being generated inside GuidesFromMesh, they are new guides generated in EditGuides. Since each operator is individual, GuidesFromMesh cannot act on EditGuides.
The Detail node is designed for cases like this, allowing you to change the point count globally. Same as the previews case, the order of operator matters. If you want the Detail node to affect the planted guides as well, you have to use it on top of Edit Guides. The detail node have parameters to determine the point count on the viewport and on the render. Please find more details in the documentation:
https://ephere.com/plugins/autodesk/maya/ornatrix/docs/2/Changing_Strand_Detail.html
Jeordanis Figuereo (Product Designer. EPHERE Inc.)