Touch disease in devices otger than 6/6+?

I have been fixing iDevices for about 4 years now and I have just now dealt with 2 touch disease phones, a 6 and a 6 plus. I am not learned enough to fix these myself and have asked for quotes for both. It got me thinking though, and I would like to bounce my thought off you.

I have been experiencing a ghosting effect after fixing some iPads. It has happened in all models except the newest. I always test the screen before setting the glue, but the glitch is not always apparent. Sometimes it takes a few days to appear, sometimes it is right away.

I really haven't paid too much attention, I have always thought it was a defect in the new screens, but my screens are from a good source. The two most recent ghosting iPads had bent frames and this journey through 6/6+ touch sickness has me thinking.

**If the weak link in touch screen phones are ic chips and their connection, is it possible that ic chips and connections are the weak link in iPads?**