The decisions a coating project turns on

If the core tolerates water, coat aqueous. It removes a whole category of plant, testing and operator exposure, and it is where regulators and new lines have been heading for two decades. Go solvent when the core forces you to, not to save cycle time.

Use HPMC unless the active or the market gives you a reason not to. Move to PVA when the product is hygroscopic, when you are exporting into a hot and humid stability zone, or when an HPMC film has already failed a stability pull.

If you coat one or two products at very high volume and have a formulation team with spare capacity, blending in house will be cheaper and you should do it. If you coat many products, or your QA is already stretched, the per kilogram premium buys back more than it costs in qualification, investigation and variability.