Thermoquad question

Is the lean condition momentary?
Or longer than a second or two?

I’ve been reading. Trying to figure out the issue.
The only idea I can come up with so far is the actual amount the butterflies close on each throttle blip. These are old carbs and the linkage could be a bit loose allowing the throttle blades a ever so small amount of resting positions however small & minute. There is a lot of external parts on a TQ that can be effected. Worn, bent, out of wack/adjustment.