The Finer Points of Repeat and Registers

The repeat change command, ., has an interesting side effect when combined with pasting a register: if you type "1p to put register 1, and then press ., you'll see the contents of register 2. You can repeat this up to the ninth register. To understand how this works you need to look at how the registers work.

Register 0 is used for storing the contents of the last yank command. So if you press yy to yank the current line, it will be stored there. Register 1 stores the most recently deleted text, and subsequent deletes cause the contents to be copied from 1 to 2 and so on, up to 9.

If you’ve gone on a delete frenzy, then you can actually get the text back by repeating a put. Try typing "1p and then pressing . a few times and you should see what I mean. If you combine this with undo then you can cycle through each line: "1p.u.u..

The reason this works is because . increases the number of the register for you. This is from the redo-register documentation:

If you want to get back more than one part of deleted text, you can use a
special feature of the repeat command “.”. It will increase the number of the
register used. So if you first do “”1P”, the following “.” will result in a
‘“2P’. Repeating this will result in all numbered registers being inserted.

This “special feature” unlocks lots of interesting tricks that are apparently similar to the Emacs yank-pop command, which allows you to cycle through the "kill-ring". The size of the kill-ring is configurable -- if you want to read more about it refer to the KillingAndYanking section in the Emacs Wiki.