Maximum disks count in diskgroup / rebalancing performance fear

Hi,

regarding this doc https://docs.oracle.com/database/121/OSTMG/GUID-BC6544D7-6D59-42B3-AE1F-4201D3459ADD.htm#OSTMG94136 about ASM limits, I have the following questions:

Is there a correlation between increasing count of disks with external redundancy in a diskgroup and a possible decreasing of ASM rebalancing performance or general diskgroup I/O performance?

Multiple adding disks to a diskgroup, what will be better:

Adding disks one after another (alter diskgroup data add '//./disk1'=> wait until completion => alter diskgroup data add '//./disk2'=> wait until completion => alter diskgroup data add '//./disk3'=> wait until completion => ...)  or adding all disks with one run (alter diskgroup data add '//./disk1' ,'//./disk2','//./disk3')