Having a standard intro just to have an intro definitely rather hurts your channel. The first few seconds need to hook the viewer with something he was searching for when he clicked on the video link.
A teaser works best for this purpose. A very (!) short intro afterwards can strengthen your branding.
So intros are more important than outros when they really are targeted towards the viewer of this particular video.
Outros then help to lead the viewer that was caught by the intro and kept interested by the content to other videos of yours (like
@ThioJoe mentioned always use the playlist link to the video i.e. the link of the video
in the playlist
not the link to the playlist). It's absolutely okay that subscribers who already know your content leave at the end card but the opportunity to hook new subscribers is worse the audience retention drop.