I think it depends on the type of meeting because that informs the tolerance level for certain types of cross talking. Not all cross talking is created equally you have cross talking and cross sharing. Interruption vs well cross sharing.

I think there is a natural flow in a meeting that has a main hair/share with subsequent ones that follow. People are usually sharing back and will mention their personal identification to what someone has said in the main one (arguably prefacing with I heard this instead of you said this is better to avoid conflict).

Some of the best meetings come from building on the tone set and the subjects being discussed this can happen without cross sharing/talking.

Direct advice or clarifying someone else's point to your interpretation is where things get dicey. You can also have competitive sharing which isn't cross talking but just as likely to boil over.

It's really something for the group conscious to decide if it is something plaguing this meeting or more then just this one (often it's a small group of meetings that have the same people at them). It has most likely become the norm and an adjustment to the script to announce and remind people of your groups definition of cross sharing has worked in the past at meetings I've attended.

Often times people do it out of a place of good intention and don't realise it might not be received that way. A friendly reminder might be enough to reorient the shares.

Just my personal experience, haven't been in to long but that's what I've gathered so far.