Singles with most Top 10 weeks in official charts
(Australia, Austria, Belgium (Flanders), Belgium (Wallonia), Canada (post-2007), Denmark, Finland, France, Germany, Ireland, Italy, Netherlands, New Zealand, Norway, Spain, Sweden, Switzerland, United Kingdom, United States)
#1 Scream & Shout - 267 weeks
#2 ...Baby One More Time - 237 weeks
#3 Womanizer - 160 weeks
#4 Oops!... I Did It Again - 149 weeks
#5 Toxic - 131 weeks
#6 (You Drive Me) Crazy - 113 weeks
#7 Everytime - 112 weeks
#8 Sometimes - 85 weeks
#9 Lucky - 83 weeks
#10 Me Against The Music - 79 weeks
#10 Born To Make You Happy - 79 weeks
#11 Gimme More - 74 weeks
#12 Piece Of Me - 64 weeks
#13 My Prerogative - 56 weeks
#13 Till The World Ends - 56 weeks
#14 I'm A Slave 4 U - 48 weeks
#14 3 - 48 weeks
#16 Stronger - 41 weeks
#16 Circus - 41 weeks
#16 Hold It Against Me - 41 weeks
#17 Overprotected - 29 weeks
#17 I Wanna Go - 29 weeks
#18 I'm Not A Girl, Not Yet A Woman - 28 weeks
#19 Do Somethin' - 11 weeks
#20 Work Bitch - 9 weeks
#20 Break The Ice - 9 weeks
#21 Boys - 7 weeks
#22 I Love Rock 'N' Roll - 6 weeks
#23 Don't Let Me Be The Last To Know - 5 weeks
#24 Someday (I Will Understand) - 3 weeks
#25 Radar - 2 weeks
#26 If U Seek Amy - 1 week
I did this a while ago for Europe but I figured I'd add U.S. + Australia + Canada + New Zealand. Note that it's almost impossible to find Canadian chart archives for the 90s/early 00s so only singles post-2007 include Canada, which is when the Canadian Hot 100 was officially launched. Since the sales climate changed so much over the years, I think this is a good way to determine what her biggest hits are.
Sometimes, Lucky, Me Against The Music, Everytime and Born To Make You Happy being so high without support from the U.S.
MAKE ME