[obcbeatle]

SNIP
1966
1 1 - 109 1-88 21 34
2 110 - 196 89-176 20 101
3 197 - 283 177-264 19 183
4 284 - 370 265-352 18 279
5 371 - 446 353-429 17 363
6 447 - 522 430-506 16 444
7 523 - 598 507-598 0 517
SNIP

I'll go out on a limb here :-)

1966
Series 1 was cards 1 - 109, Checklist said 1-88, that's a difference of 21 cards, I have no clue what 34 means :-) March/April release?
2 110 - 196 89-176 20 101 April/May release?
3 197 - 283 177-264 19 183 May/June release?
4 284 - 370 265-352 18 279 June/July release?
5 371 - 446 353-429 17 363 July/August release?
6 447 - 522 430-506 16 444 August/Sept. release?
7 523 - 598 507-598 0 517 Sept. release?

I'm obviously grasping at straws here :-) Seems like one of the Summer series releases would have been a TON of cards for that series as I always seemed to get a bunch of dupes in the Summer :-) For example, in 1968 I had a lot of dupes for a specific series, even of stars and hofers in that series. But probably more likely I just bought more cards in that series, hence I had fewer dupes in other series. Which kind of relates to my original question of trying to determine when I might have bought cards for each series (like a monthly timeline), then scan the cards I pulled and figure out when that year I pulled them. Again, I probably have way too much time on my hands right now :-)