I know some people virtualize older OSes with the corresponding hardware of the time order to simulate a specific computer model. In my case, I'm hoping to virtualize bootable backups of old Macs of mine (as well as play around on fresh installations of older OS versions) and I don't care to preserve the experience of the slower hardware specifications of the time but would rather take advantage of my current Mac's power.

If I'm not mistaken, when selecting the OS version being installed in VMware Fusion, the settings default to a virtual hardware configuration that more or less match that time period, right? Is there any reason I shouldn't just pump up the CPU cores, RAM, et cetera, to the maximum allowable in the VM settings in order to get the fastest virtualization experience?

Does VMware Fusion have a dynamic "Maximum available" VM hardware setting that can either assign the maximum without me needing to specific select it, and/or dynamically adjust based on the available resources (which might change as I open and close applications on my actual computer)? Thank you!