Where did that ever actually happen?

AFAIK, no target was ever hit by both forces within the same 24h period.
Well, think about Dresden... got some attacks by day and night
or think about hamburg... thses are two easy examples... you will find more.
So your "never" is wrong
also, bombing round the clock doesn´t say you bomb the same city, you can also fly to cologne and at day to essen... for both cities you have the german defence on the deck... so the germans have to fight "round the clock"...
if everything happen at night the germans have some "sure" times... if the allies try to bomb in a full moon night they get slaughtered... also the big advantage of long range fighters have nil impact... the germans have two engine planes, but their main daylight crews will not suffer the same way they did in the time december 1943-may 1944... so the quality of the german pilots will be much higher...
the destroyed industries will be much lesser... so more produced goods, weapons, ammo... less destroyed fuel means better trained and more combat ready planes.. and so on... no - americans using british methods mean a much stronger german airforce and a much less experienced allied daylight airforce...
as you can learn from vietnam, the number of tons dropped on an enemy say nothing... as long as you just hit mud or nothing "important"...