These are great examples, but even pertaining to Fleetwood Mac, Landslide wasn't ever released as a single, yet is probably their "biggest hit". Go Your Own Way only got to #10 US and #38 UK, but is probably close with Landslide, in terms of popularity.. Really there is no rhyme or reason as to what is successful as far as singles are concerned with this band... I think Gypsy could have been a bigger hit had it been released as the first single off the album. I also think Straight Back should have been the third single, instead of Love in Store... It's nice, but I just think they needed something more "punchy". Personally, I think it would have been advantageous.
I found this, the Billboard US charts the week Gypsy peaked, and I think it's rather interesting:
1 1 JACK AND DIANE John Cougar (Riva)-14 (4 weeks at #1) (1)
2 2 WHO CAN IT BE NOW Men At Work (Columbia)-16 (2)
3 3 EYE IN THE SKY The Alan Parsons Project (Arista)-17 (3)
4 6 I KEEP FORGETTIN (Every Time Youre Near) Michael McDonald (Warner Brothers)-12 (4)
5 11 UP WHERE WE BELONG Joe Cocker and Jennifer Warnes (Island)-10 (5)
6 9 HEART ATTACK Olivia Newton-John (MCA)-8 (6)
7 7 SOMEBODYS BABY Jackson Browne (Asylum)-13 (7)
8 8 YOU CAN DO MAGIC America (Capitol)-13 (8)
9 10 I RAN (So Far Away) A Flock Of Seagulls (Jive)-16 (9)
10 5 ABRACADABRA The Steve Miller Band (Capitol)-22 (1)
11 13 BREAK IT TO ME GENTLY Juice Newton (Capitol)-10 (11)
12 15 GYPSY Fleetwood Mac (Warner Brothers)-8 (12)