I have done so many Exchange installs in the past 16+ years and I have never seen an installation go as quick as CU7 for Exchange 2019.
In unattended mode of the installation, normally you have to wait in the section “Copying Exchange Files” and 16% seems to just stay there, just like “Finalizing Setup” that stays on 2% forever.
My lab has 4x Core CPU and 16GB of ram and this is how fast Exchange 2019 is, can you imagine if it was running with more CPU cores and ram?
Microsoft have really made improvements here. Below is my completed unattended setup, it took 40 minutes, start to finish.
Happy Installing Exchange 2019.
Hope it helps.