"They want each launch to get maximum attention and the best way to do that is to space them out," Baker said.
He also noted that, like other computer makers, Apple is tied to Intel's processor release cycles. "Despite their best efforts they still remain, to at least some extent, although not as much as the Windows guys, beholden to Intel's refresh cycle," Baker said.
By spacing out product announcements -- MacBook Pros this week, for instance, a new iPad likely soon after -- Apple also reduces pressure on its supply chain and retail stores, Baker added.
Apple's iMac desktop line is also nearing the time when it could be updated. The MacRumors Buying Guide, which tracks the intervals between Mac refreshes, currently notes that it's been 211 days since the last iMac revamp, close to the 226-day average.
The iMac's last update was in July 2010.
"iMac sales have been much weaker than MacBooks and I think refreshes that keep that line relevant and current are more important to it than MacBooks, since the underlying demand for desktops is inherently weaker than the notebooks," said Baker.
In the last quarter for which Apple has released sales figures -- the fourth quarter of 2010 -- the company sold 1.2 million desktop systems, the bulk of them iMacs, compared to 2.9 million notebooks. Desktop sales that quarter were down 1% from the year prior, while notebook sales were up 37% over the same quarter in 2009.
Apple has foresworn public events for announcing most upgrades to its existing Mac lines, instead relying on press releases and new information on its e-store to carry the load. One recent exception to that rule was last October, when CEO Steve Jobs -- now out on an indefinite medical leave -- debuted the new MacBook Air by calling it "the future of notebooks."
Apple will also host its annual stockholder meeting today starting at 1 p.m. ET. It's not known if Jobs will appear, although he did attend a dinner last week with President Obama.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@computerworld.com.