Several years ago on the hard surface tracks, the rules started allowing for folks to "run up" in engine class. e.g: a stock bore Busa could run in 1350, 1650, 2000, 3000, and sometimes 3000+. Then recently, a new engine category "twin" was added at these tracks. This opened up a whole range of open records for folks to run against, assuming you had a 2 cylinder bike.
Now if you also carry 2 different tail sections in your trailer, you can run Modified Streamlined and Altered Streamlined at the same event. Pull the fairings and you are in Modified. Have a 1 gallon fuel tank available, and without the fairings you can run Altered.
There are 10 engine classes from a 250-3000+, add the "twin" and you have 20. Go between M, A, MPS, APS ... you now have 80. Change between Fuel and Gas, it raises to 160. At Loring, they have traps (records) at the mile and 1.5 mile, now you have 320 at a single venue.
Of course, since it cost $$ to switch classes, it get's real expensive really fast.
However, once the record book is filled up with no open records remaining, it starts to become more and more difficult to get lots of records at a single event.
In all fairness, some folks who have held lots of impressive records (Like Scott G.), didn't have all these types of rules (or categories) for most of their racing careers and they didn't (or couldn't) set gobs of records at a single event.
On a personal note: I have no clue how many records I have set. I don't even think about switching classes. I just try to get faster and learn.