Can RAID 1 (mirror) improve average access time?

Although they say RAID does not improve access time, supposedly, RAID 1 is able to improve average access time (but not random access time) during the read.

As you know there are two same copies of data and two member disks in RAID 1.

 When read operations are grouped as described below:

• the first half of the data is served by the first disk
• second disk is responsible for the second part of the data

then the average length which a read head should go to find a sector is reduced in half.
Based on the above considerations it is not possible to improve rotational latency. Anyway, performance improves because less head travel is needed. As for writes, it is not possible to improve performance since both disks should be updated.