The number of pages per pager is determined by the optional second argument passed to the [Paginate] method, falling back to the pagerSize as defined in your [site configuration].
{{ $pages := where site.RegularPages "Type" "posts" }}
{{ $paginator := .Paginate $pages }}
{{ range $paginator.Pages }}
<h2><a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a></h2>
{{ end }}
{{ with $paginator }}
{{ .PagerSize }}
{{ end }}