For me, definately OUT of the pots as keeping them in will stifle them.
For bunches of stems I would remove the lead / sponge etc, trim off any lower leaves, and then group them in 3 to 4 stems. Push the bottom of these groups into the substrate and if need be use a small stone / pebble to hold them down. Most stems plants will root after a while so you can try removing the pebble. I would space each group of stems 2-3 inches apart.
For rooted plants, trim the roots slightly, then do the same as above: you may not need the pebble for this type of plant. Trimming the roots encourages new root growth.
For carpeting plants such as Glosso: Cut up each plantlet and plant individually with tweezers. It's a pain but if you have the right light, CO2 etc. you'll get a full carpet in a few weeks. Expect the odd plant to float up. Just keep re-planting until they take hold.
Andy