using Calc to summarize data in a PostgreSQL table containing 17,071,231 records  with 67 fields. Only 54 fields are of interest for this analysis which consists of executing this SQL query:
  select fld, count(fld) from table group by fld order by fld;
This gives me 2 columns like this example:
ALAMANCE   236445
ALEXANDER   57281
ALLEGHANY   18589
ANSON       36426
ASHE        46159
AVERY       28783
BEAUFORT    79544
BERTIE      29424
which I copy/paste into a new sheet renamed to match the field name.

I have F3 in LO set to REPEAT the last action.

After collecting much data, it's time to add analysis: using the above example, I change the first row to:
ALAMANCE   236445  =len(A1)   =B1*C1

To save time, I make extensive use of F3(REPEAT) like these actions:
* copy C1-D1, switch to next sheet, paste into C1-D1, next sheet, REPEAT...
* back to initial sheet, add a row above row 1, next sheet, row 1, REPEAT...

If you are picturing this activity, you can see how this approach can proceed quite fast...
One time, I missed and clicked on the column rather than the top cell; REPEAT proceeded to paste into the entire column (16M rows) -- 100% CPU, Calc just died.
Restart Calc & recovered 7 documents; but not this document. Open Recent recovered to the last save.
Repeated the lost steps.   
* initial sheet, add column header labels, copy row, next sheet, paste, REPEAT.
After adding headers to about 1/2 the sheets, instead of clicking on row 1, hit the area just above + F3 which proceeded to paste into the entire sheet -> 100% CPU. Got "Not responding". xkill had no effect on the window (never saw that before). Tried Close button which gave me the terminate dialog.

Build: https://gerrit.libreoffice.org/gitweb?p=core.git;a=log;h=5ff701226b00963312cb2a78e77966d012b79c82

Operating System: Mageia 10
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.2.0
Qt Version: 6.6.2
Kernel Version: 6.6.28-server-1.mga10 (64-bit)
Graphics Platform: Wayland
Processors: 20 × 12th Gen Intel® Core™ i7-12700K
Memory: 125.5 GiB of RAM
Graphics Processor: AMD Radeon RX 6600 XT
Manufacturer: Dell Inc.
Product Name: XPS 8950

Maybe there should be a quick sanity check when something like Paste to ALL (column, row, sheet) could cause aggravation and data loss giving LO a bad reputation with the user.  Hitting this flaw which results in data loss and wasted time twice within about 15-20 minutes was frustrating.  Just saying... :)

Hopefully, the above is clear enough to build a test case.