Here is a bathroom l just finished in West Seattle. This substrate needed alot of floor prep prior to the marmoleum installation. 8 hours worth of floor prep. Reason- the contractor elected to just pour self leveler and not trowel the self leveler once the floor had been poured. If self leveling concrete isn’t smoothed out the rocks in it end up creating high points. I in turn then have to float out those high points in order to prevent bumps and peaks in the substrate. Marmoleum will telegraph any imperfection in the floor once the adhesive bonds the marmoleum to the substrate.  Thus it is crucial l get the substrate as flat as possible. So if you or your contractor uses self leveling concrete be sure to trowel the lever a little bit to ensure the rocks in it are below the surface once it’s cured and hard. Try to eliminate any high spots or bumps while you trowel the self leveler. This makes a huge difference in the amount of time l have to spend prepping the substrate prior to the marmoleum installation.