I, mentally, split volunteers into two groups.
Type 1
In general likes children. Can be found helping local scout/sport/play group. Helps PTA, reads with an year group that needs the help. Supports the school staff, the decisions they make, understands the context in which they are made and takes the trouble to be informed with current educational trends rather then continuously referring back to their own school days.
OP, I think that sounds like you, thank you, my kids have benefited hugely these volunteers.
Type 2
PFB starts school. Mother volunteers to help, school pays for lots of expensive CRB checks. Initially volunteers to help out 2/3 times a week. Feels aggrieved that mostly is stuffing book bags but has n't troubled to learn correct Phonic sounds. Whilst in classroom is continuously turning round to assess which kids are where in the behavior/ intelligence/ neat hair stakes.
Has a massive spread sheet at home collating child, book band, parental car choice, school coat brand. Calculates who 'socially' would be the best match for PFB. Commences Project 'My New Best Friend', ignores current choice of friends, invites to tea new BF, peppers conversation with encouraging new BF phrases, joins ballet group, etc.
As new friendships settle down and 'pecking order' established drops out of volunteering due to unspecified reasons.
We have lots of these at DDs school.
, they winge about the teachers, the behavior of other kids, school policies, etc they see this as being 'engaged' but actually are pretty toxic and waste a lot of school resources.