number of roughtime servers for a good enough ecosystem?

[fge...@gmail.com]

Hi,
is there an expected number of roughtime servers, when the roughtime
ecosystem can be qualified as good enough/too few servers/too many
servers?
https://roughtime.googlesource.com/roughtime/+/HEAD/ECOSYSTEM.md
currently doesn't cover this.
Iiuc the ecosystem design implies, that there can't be too many
servers. Do I understand correctly?
thanks!