pre configuration mode: single system vs standard

Hi,

My business conrims that they do not need the system when we start the upgrade. so i assuem no downtime minimize is required since no one doing any thing in system.

i understand that down time minimized method can be considered when the business needs the system.

since they do not access the system during the upgrade, can i consider single system mode.

what is the impact of single system?

does the total run time changes?

which run time is much faster?