Is the Walker LP system necessary if one already uses a good RCM?

If you’re into multi-step procedures, look at Audio Intelligent. 2 cleaners and a rinse. I’ve used it on reasonably clean records and it’s good, but I also like the AI #6 one step. Works absolutely fine, but I don’t buy flea-market trashed records. 

Lloyd died recently. I used the 3, and then 4 step, Walker products-really liked his unidirectional applicator-- for quite a while, but switched years ago to AIVS #15 and a pure water rinse. I could not tell the difference. I use a big Monks Omni plus ultrasonic. 

Walker is not expensive but seems like a major hassle.

It is a great product and yes it takes time especially if buying second hand lp's and doing the whole process. Never exceeded 10-20 lp's both sides cleaning, enzymes have limited life time before dying (some hours), though i am not a chemist to verify that. After that, only the pre mixed solution or/and ultra pure water is fine if required. Transparency, inner detail, focus, are all increased, surface noise is dead silent, no residue, no static build up, and lp's come clean and shiny and stay that way for a long time. More experienced people on the subject may have found better solutions but after tried and used some of them myself i find the Prelude perfect.

Absolutely not. I have become to believe that the most important aspects of record cleaning are vacuum drying and avoidance of used fluids. How you agitate the fluid either by bidirectional brushing or ultrasound does not seem to make much difference. @whart has most of the bases covered the only problem I see with his system is that the KL Audio reuses it's fluid. It does pass it through a filter which will pick up particulate but it will not remove substances that are dissolved in the fluid. Fortunately vacuum drying removes most of it. The KL Audio by itself is not satisfactory. Any system that uses an evaporative drying method like blow drying is not satisfactory. The water evaporates but most everything else does not. I think the KL is the best of the ultrasonic cleaners and the Keith Monks is a great vacuum dryer but the whole affair takes up more space, is more complicated and takes much longer to clean and vacuum both sides. 

As for Walker Audio, Lloyd came up with a landmark turntable but the people around him turned the company into a tweak outfit in the worst way. I am sure he is rolling over in his grave.

Record cleaning fluid is a big can of worms. Distilled water is safe. Some additives may leave a residue on the record. I have begun to believe this is not a problem as long as it does not build up on the stylus. In some instances it may actually be of benefit but I am not sure....yet.