Attic ventilation question

Wanted to get some opinions on a practice I have been running into lately that I do not like.

I have been seeing homes with both a ridge vent and passive vent boxes installed. I am of the opinion that this causes poor attic ventilation because convection can cause the passive vent boxes to become inlets for the air and set up a convection cycle between them and the ridge vent above them. Causing all of the lower attic area to be poorly vented.

Opinions? In some of the homes the ridge availible for the ridge vent was not long enough. So they have added the passive vents in an attempt to increase the exit ventilation area. But I am not sure I think it works, that if the ridge is not long enough, it should ne have a vent and they should only use the passive vent boxes.

Hip roofs have this problem for ridge venting. So long as the roof has adequate soffit venting, and the additional roof vents are placed as close to the ridge as possible, there should be no short circuit problem with the venting, and both the ridge and box vents are contributing to the proper air flow.

Jim King