OK my question is:

NFPA 2021 5.3.3.5.10 cylinder or liquid header. Category 3 systems shall comply with 5.1.3.5 and 5.1.3.5.9, except as follows:

(1) Gas cylinders or cryogenic liquid container headers shall be in accordance with 5.1.3.5.9, with sufficient cylinder connections to provide for at least one average day's supply, and with the appropriate number of connections determined only after consideration of the delivery schedule..... etc. (No mention of a minimum cylinder requirement)

However: 5.3.3.5.12: Category 3  systems shall comply with 5.1.3.5 and 5.1.3.5.10.

5.1.3.5.10.4 (1) Two equal headers in accordance with 5.1.3.5.9 each with a sufficient number of cylinder connections  for one average day's supply but not fewer than two connections.... etc.

So, can Category 3 facility have only one cylinder for header as per 5.3.3.5.10  or two cylinders as per 5.1.3.5.10.4(1) ?