Goal: standardize around one filter holder and system. I prefer square drop-in filters. They take up less space. Prefer glass.

What I have: a hodgepodge of adapter rings, a Cokin drop in holder that can accommodate 84 x 120 mm filters; a set of Galen Rowell ND grads sized 84x120. All of this was stuff from my 35mm kit.

Current Lens: Fuji 150 f5.6 with 52mm threads. I have a 52mm ring to connect to the Cokin holder.

Shooting 4x5

I'm good-to-go with the ND grads I have but want to add yellow, red, etc for B&W work. I'm concerned about the filter holder, that as my lens kits grows over time that it won't be sized properly to cover larger LF lenses. I don't want to invest in colored 84x120 filters and then find out that I should've sized larger for bigger-sized lenses.

Is there a "standard" filter holder size (and drop in filter) for 4x5 that I should be looking at?