Many go to mikve (perform ritual immersion) every morning. One reason for this is voluntary continuation of a cancelled decree, Tevilas Ezra, meant to limit conjugal relations by requiring immersion between relations and prayer.
Besides another reason for it, common daily immersion preserves modesty by preventing that day's mikve-goers from knowing who else had relations the previous night.*
If everyone was anyway immersing every day, how was the decree effective in limiting conjugal relations?
Are there any sources that explain the decree's effectiveness based on immersion having been a major ordeal in those times?
* However, women (who can be presumed to have relations on the night they immerse) do little to prevent meeting each other at the mikve, and I don't know of a custom for women to immerse every night.