If you dig through a collection of ADFs in search of a particular file I would recommend to use
?xxxx*.ADF rather than @xxxx.ADF
The chance to miss an ADP or Init-file is pretty high if you scan only for files which include "@" + the card-ID + the extension .ADF !
Some cards won't install properly without having the entire option disk. The typical symptom is a lack of function - coming either from missing ADPs (also: old and outdated *.DGS-files etc.) or improper setup at all.
Cards known as critical:
Basically all memory cards.
The most of them come with a base-ADF plus an ADP and / or Init-File.
My collection contains a lot files - to which the ADPs and Init-Files might be missing. The chance to run into such a file is the higher, the rarer the card is.
It is almost impossible to find an option disk for a lot cards today.
Basically all kind of "on-card processor upgrades"
Cards, like the AOX MicroMaster and the Kingston MicroMaster, which are the later-level AOX-cards after Kingston took over the business from AOX.
Impossible to install or bring to function without the entire option disk.
Many "intelligent communication cards"
Most serial communication controllers with own processor require a particular setup or a modified SC.EXE on the reference. In most cases they also require a special testing software and sometimes drivers for the used operating system. Almost no chance to get them working without the option disk.
IBM XGA-2 card
Older versions of the reference have too old files, originally written for the XGA-1.
These files are namely XGA.DGS, XGAANI.DGS and VGA.DGS
The better way is to use a fresh copy of the reference and use "copy an option disk" to bring the files from the XGA-2 Option Disk onto the reference. Better use a fresh copy, because the installation of the XGA-2 files takes a lot room for temporary files.