[exodust]

Perhaps oversimplified. The manager might not want you tethered to his/her in-box like a puppy on a leash.

"When things happen", sounds risky. You don't want to be drip-feeding emails about individual things as they happen. Perhaps this is obvious, but you'd keep your own notes and try to condense into a nice little list for discussion when you next catch-up.

[onion2k]

It takes some judgement for sure, but that comes with experience. It's far better to over-communicate than under-communicate until you can gauge it yourself so I'd always recommend sharing everything when it happens.

If it's too much your manager can tell you. That's how you get that experience.