Check-In Styles Limit

Hi

Would anyone know if there is an appropriate limit to check in styles? We have a user who has 144 of them and Outlook is slow to open. I am thinking that the large amount of check in styles is the cause of this as when the add-in is disabled, Outlook will open fine.

I have asked him to delete some of them but he is reluctant to do so. If I had some advice or guidance to go on, I would appreciate that.

Thanks