Would only advise when the model is complex and/or difficult to achieve. Turning parts to meshes can greatly reduce part count, but in turn you’d create an asset that is A, moderable and B, time consuming to load on suboptimal conditions. Unions are indigenous to an experience, but still possess trait B of meshes. Parts will always load the quickest and be the first to load over the mentioned instances. They’re just parts.
In this case, if this experience runs relatively fine, it probably doesn’t need to be fixed.