As a 'filker' (writer of parodies, short one-offs, Fantasy & SF based, etc.) I often find hymn tunes very useful.
If I've got a partial song, with at least one verse, I try to set it to a hymn tune (almost 60 years in a church choir means I know a lot of them). That doesn't mean that the final song will use the hymn tune, but it does mean that as I add verses I have a quick mental check for rhythm and scansion by comparing the 'new' verse to the hymn tune. If it scans then I know the scansion also matches the 'proto' verse.
If a subsequent verse has wording which must change the scansion, I can see whether to do so by splitting/slurring a note, or by going back and re-writing the proto verse.