I cannot judge what caused the crashes. There is even no information on the LibO version. If could also be caused by other programs running on your machine. My experience is that the 4.2.7 and 4.3.4 versions are running very stable.
But, what comes to my mind again is the expression: “Fail to prepare is prepare to fail!”
To avoid a loss of a file these are 3 recommendations:
1 - Check the following LibO options: Tools > options > Load/Save > General
---- Save Autorecovery every x mins (the shorter the value the small a possible loss; I use 3 min)
---- Automatically save document too ( I don’t use this, because I regard the autorecovery function as excellent.)
---- Always create a backup copy (download and read the free of charge LibO guide to understand how this works)
2 - When I work more than a day on a file, I create additional daily back ups. I use the format “filename_yymmdd.ext” and I keep at least 1 previous version.
In case the file is extremely important and I work long hours non-stop, I add the actual time behind the date.
3 - Backup the HDD of your computer to an external HDD. External HDD in the range of 2-4 TB cost mostly less than 100 EUR. (I do this almost daily and even backup external HDD onto another one.