dnd 5e – Do start of turn artifact properties work even when not in turn order/initiative time?

Introduction:

In this long-running 5E campaign, a player has received a powerful artifact sword. While the sword is homebrewed, the majority of its properties are randomly generated from the artifact properties tables in the DMG.

I’m appealing here for a mechanical ruling as to the appropriate interpretation of one such property of the sword (see the details below). Any supporting official rules text, or sage advice on the subject (I did not find any), would be greatly appreciated. If there is none, and it is a matter for the DM to rule on, then opinions would of course be welcome.

Thanks in advance!

Question:

Based on the following givens, and two provided possible interpretations, what is the correct interpretation of the example random beneficial property? Put another way, when does the given property trigger, and when does it not trigger? Please provide any rules justification for your answer.

Given:

  1. In 5E, a round of combat is 6 seconds long, which is also the theoretical length of a player character’s turn in that combat.
  2. In 5E, artifacts may have random properties.
  3. Some artifact properties reference an effect happening “at the start of your turn,” for example: from DMG page 219, the Major Beneficial Properties table,

“While attuned to the artifact, you regain 1d6 hit points at the start of your turn if you have at least 1 hit point.”

Conflicting Interpretations:

Player: an item with the above property passively heals the attuned character by 1d6 hit points every 6 seconds, regardless of circumstance (initiative, combat, etc.), until they reach their hit point maximum.

DM: an item with the above property passively heals the attuned character by 1d6 hit points at the start of their turn, which requires that play is proceeding in initiative order, and does not heal a character while out of turn-based play.

Of course, if another unspecified interpretation is correct, this is also welcome!