I am frequently in a situation where translated text contains a lot of very short segments, which I would classify as junk (for lack of a better word). Some examples of this would be various numbers containing short translatable text, acronyms, fragments of words, misspelled words or perhaps names of physical units. Generally I try to avoid cluttering my TMs with such junk entries. They cause a lot of problems later when you pre-translate and then have to correct a lot of segments which were not supposed to be pre-translated, but were replaced by these short junk entries.
I would like to have a shortcut available that would allow me to trigger Auto Propagation but NOT to update Translation Memory. In other words, I would like to have the ability to make a decision for every segment whether to save an active segment in TM or not. Such a shortcut would be equivalent to going to project settings and unticking the "update" option for Translation Memory for the very segment where the shortcut is used without actually going to project settings.