First of all, welcome aboard. I always love to here of peoples first steps into SEO and the results they get.
My site has around 450 pages, thus its would be a major job for me to amend my page titles. Sites like SEOmoz have thousands of pages, and the vast majority of them are available in SERPs. Now as far as I know SEOmoz do not change their titles, again because it would be a massive job.
Saying that, if I run an offer or a sale on my website I will generally change my homepage title to reflect the fact I have a sale on, in the hope that the Sale text will be updated promptly in the SERPs and attarct a few extra click throughs.
In summary, no I dont think the freshness of your page titles has any positive effect on your SEO. But, It may impact your Click through rate (which I guess in turn could effect your SEO...now were going full circle).
Clear as mud?