My current installation uses normal non-indexed databases for all data I want to search for (about 400 GB). They are locally stored in my 3 Macs. Apart my 3 iPads and my iPhone have partially downloaded Gropus.
Apart of that I maintain a full copy of the files in a more complex structure in my NAS, with a copy in pCloud (was Dropbox, but I got a good price for 2 TB in pCloud, less than 2 years in Dropbox).
When I add a new file to DT, I add to my NAS as well. And once a month, I export each DT database and sync them to those folders in my NAS (because I forgot to add some files or modify others in DT). That way I have DT/DTTG always available but if I’m without any of my iThins/aThings, or the file I want is not there, I can always access to my NAS or pCloud from any place.
It is not a lack of confidence in DT (DT sync better between instances than my Synology Drive/pCloud), but I maintain a, well, now about 1.2 TB of files in my NAS.