Depends on what you use LinkedIn for...
There's a lot of noise out there from social media, news media, collaboration sites, feeds of all sorts, and oh yes...there's people that we meet and spend time with (customers, prospects, vendors, ..).
If you only rely on LinkedIn for establishing connections and developing business relationships / leads, then it probably should be on a daily basis. There are the direct relationships via messages between individuals (2 or more). And there's the indirect relationships that require time in the Group discussions. The general discussion area that has morphed into social media (unfortunately) has become an (important) channel for promotion and to build visibility. All of this and we're only talking about one channel (LinkedIn). So, it does require planning (to your point Janet). You can setup automatic feeds from LinkedIn (like other channels) to feed into your email (perhaps in a rules-driven folder) to scan and follow up. That can help create focus for when you want to spend time directly in LinkedIn.
As for the other channels, this is where folks are increasingly relying on aggregators (now we have aggregators of aggregators) and more intelligent robots (automated response, filtering, and organization) of incoming streams of information.
It's an evolving balance to stay connected and informed and it's even more challenging when these content providers (including LinkedIn) keep changing the format (which changes the way the "bots" are able to mine the information and forces more folks to spend time in their applications (which can boost advertising revenue).
That being said, I "try" to apply a simple 4-step approach using LinkedIn and other tools:
Create and build relationships
Build awareness and knowledge
Provide value and maintain relevancy
Promote, Position, and Prepare