I can't speak for others on this forum but I tend not to plant anything in "clumps" and take a wider view of my garden beds. I do plant perennials (not hostas) in groups of three at an angle to a path or walkway. This generally translates to a more noticeable impact with some perennials. Astilbe comes to mind due to its airy foliage. It's often suggested that planting in groups of 3 or 5 offers sufficient impact.

Multiples of some perennials can provide a more significant impact in a garden bed as opposed to "specimen" plants (i.e., one here and another a few feet away).

reason im asking..i have several halcyon hostas..just think they would look better in a tight circle planted close to each other..im new to hostas so I wondered if they would have problems with roots getting tangled ...

I like hostas planted in groups of the same cultivar or as single " specimens"... It comes down to the overall look that you prefer. If I had more room,I'd plant more groups, as well as wider drifts of companion plants.

a clump is a mature plant ..

a mature halcyon can easily be 2 foot across.. AT THE GROUND ...

as a collector.. i have no idea why one would own more than one ...

but if you insist.. i would put them 2 to 3 feet apart ... and in about 3 years.. you will probably have about an 8 foot circle..

you ought to be able to google 'hosta halcyon' .... and get a flavor of its vigor ... width.. etc ...

otherwise ... plant them all in the same hole and forget about them competing with each other.. if you care to worry.. worry about the trees you are growing them under...

ken