It depends on the song, but I think in some cases, reaching five stars on expert is more monumental than striking gold. That first five-star finish says you've finally figured out the song's patterns, and can play them consistently enough for a good performance. Now it's just a matter of time and practice before you're polished enough to go gold.
On that note, last night I finally eeked out that fifth star on "Highway Chile," playing expert pro drums. I still can't play the ending worth a darn, but the rest of the song I've got licked!