This depends on several things, the two most important imho are: 1-what kind of investor he is 2-what kind of relationship do you want to have
1- There are some investors that are all about spray and pray. They will have 30/50 or even 100 investments. There is no way they can be on top of all of them, so they are more money focus, and if you really need their help then you can ask them. The other extreme is the one that has only a couple and spends time every week because he thinks that you are their lottery ticket. (And everything in be middle)
2-What kind of relationship you want to have
Here what you need to address is the reason why you took money from this person. Was it just for the $$? Advise? Connections? Industry expertise? Guidance? Knowledge on a specific area?(HR,Sales)

Depending on who they are and what kind of relationship you want (and why) you should adapt it to that goal. Once a month investors updates is a common one, but don't settle for what everyone does. Do what is the best for your company.

One more detail. I believe in different investors for different stages of the life of a company. Someone that knows how to build from scratch not necessary is good for scaling. So the involvement in time should also changes as their value also decreases/increases. This applies in time (as in stages) as also in how intensive or hands on they should be.