Cleaning LPs: How hard should one 'scrub'?

I've been cleaning records for months now, but I've always wondered what the correct level of 'scrubbing' is.

For a few months I steam cleaned with great results but got tired of wet labels and switched to the Walker 4 step method.

How much do you just rely on the cleaning agents doing their thing versus elbow grease? To get dirt loose, do you just have to lightly move the brush over the record (and while spinning on the RCM?) or should hard pressure be applied? The Walker brushes don't look like they'd get down between the grooves without some amount of pressure but I'm always afraid to damage the LP....

Thanks in advance for your thoughts.
Do your self a favour and use disc doctor.
With Walker P4 as you use on a 16.5 I don't apply too much pressure. I w/step 1 and 2 soak it let it spin for about 10-15 seconds each and then agitate the fluid till it foams up the vac., 3 and 4 I just spread it on and vac it off. My concern is applying too much pressure on a RCM is what does it do to the bearing and second vinyl is somewhat soft and I think it would be easily distorted with too much pressure. I am interested to learn of others opinions on this, this a topic that divides me as to which is better. Maybe I need to scrub harder?
Madfloyd, applying just slightly more pressure than the weight of the Walker pads by themselves is what I've found to work well. The fibers of the Walker pads reach into the grooves without applying significant pressure.

Think about this more as "agitating" the cleaning fluid in the grooves. Allow the cleaning fluids to do the work and the cleaning pad action only needs to be gentle. For the scrub after applying the Prelude Step 2 solution, I use a back and forth stroking action sufficient to build up a froth in the fluid. For the enzyme Step 1 and the Step 3 and Step 4 rinses, I'm quite gentle - just stirring things around thoroughy in the grooves. I've also found it best to be sure to use enough fluid in each step to "fill the grooves" -- using too little fluid often results in inadequate cleaning results.

In my experience, scrubbing harder (within reason) will not do any damage, but I've found that doing so doesn't clean any better when one is using one of the better cleaning fluid solutions, like the Walker Prelude cleaning solutions you are using.

I use a VPI 16.5, Disc Doctor fluids, separate fiber pads and vacuum tubes for cleaning and rinsing and "scrub em' like they're dirty babies". I have never damaged an LP and they are all as quiet and come from as black a background as you can imagine.