One thing I used to use a lot in supcom was pausing an engineer when I was low on a resource. So I could select a number of engineers and pause them while the 1 engineering building say metal or energy structure could finish first and then un-pause other engineers. (which is more effective than all of them trying to build at once) This becomes really useful when you've over built engineers, have a good build queue going on them & don't want to cancel & lose the it all.
Prioritizing certain structures / units is a good idea, but manually pausing (individual) engineers might not be the ideal way to do it.
