How far should one aggregate a route table? [Network aggregation / summarisation]

Hello fellow network rats, I have a question regarding how for one should summarise a network.

According to our lovely professor the following network:

10.0.4.192 / 255.255.255.192
10.0.0.128 / 255.255.255.128
10.0.0.0 / 255.255.255.128
10.0.1.0 / 255.255.255.0
10.0.5.0 / 255.255.255.0
10.0.6.0 / 255.255.255.0
10.0.4.0 / 255.255.255.0
10.0.10.0 / 255.255.255.0
10.0.2.0 / 255.255.254.0
10.0.8.0 / 255.255.254.0

Will be summarised to:

10.0.0.0 / 255.255.252.0
10.0.4.0 / 255.255.254.0
10.0.6.0 / 255.255.255.0
10.0.8.0 / 255.255.254.0
10.0.10.0 / 255.255.255.0

after maximal prefix aggregation. Couldn't it be summarised to just 10.0.0.0/21?

I have a course in internet protocols and our lovely professor isn't answering questions so this is my last resort. Also if by any chance my professor is reading this; u mom a hoe