I've used the same AutoBarn Cheap'ish $120 SAAS Baffled Oil Catch Can again that I had on my D22 for about 5 years, fitted one again (in March 2020 I think) on my ZD30 CRD Patrol I got last December 2019.
It has a drain hose that sits in the Nearside wheel arch, I'd say I drain about 20 - 30ml each time I remember to look, so maybe every 3000 - 5000k's.
I figure one is better then none fitted.