They don’t amount to anything?
A standard 15 minute(max) objective mode game or 2 halves of stopwatch(max 30 minutes)…
15 minutes = 180 credits normally. With this event 180 becomes 360 credits per 15 minutes. Stopwatch being 30 minutes max would make it 720 credits.
That doesn’t include your ‘skill bonus’ which is also doubled.
In a 3 hour period you could play up to 5 stopwatch games if all 5 games ran to max time. That is with leaving 30 minutes out for warmup/lobby/load times.
Those 5 games, or more simply 2 and a half hours of gameplay, would equal 3,600 credits.
The most you could earn in one cycle of missions is 3,000 credits. The odds of that happening? Extremely slim.