In my opinion many of these so called inhouse calibers are not inhouse.If you think about how many parts are in a simple time date caliber.Just imagine the Investment brands would have to make in new machines,just to make all the parts.The cost is huge.I would rather say many brands are assembling their own calibers,instead of buying the finished product.
This is a very grey area in modern watchmaking,and brands will never tell the truth,and nothing but the truth about their watches.

Bremont and Tag are just two of the brands who deliberately told lies about their calibers,untill watchmakers found them out.Many so called inhouse calibers are just copys of old designs,and i bet many parts are made in the far east.Watchmakers cannot be fooled,and they will recognise many of these calibers in the future.
I personally am not a watchmaker,so i leave the judgement to what i can read on the net written by watchmakers who have seen and worked on them.
Inhouse has become a selling gimmick for many brands.It gives prestige,and a good selling point in the watch brochures.In the real world there are very few brands that deserve the title of true caliber manufacturer.In fact i read once that you could count them on the fingers of one hand.