Is there a time limit for a Mauler Archetype to stay in Battle form?

Question

At 3rd level, a mauler familiar gains the Battle Form ability:

Battle Form (Su)

At 3rd level, a mauler gains the ability to transform into a larger, more ferocious form and back as a standard action three times per day. In battle form, the mauler’s size becomes Medium and it gains a +2 size bonus to its Strength score. Since many familiars are Tiny or Diminutive, be sure to check for any additional Strength and Dexterity adjustments for increasing in size from Tiny or Diminutive to Medium. This is a polymorph effect.

Is there a time limit to stay in Battle form? Can he stays in Battle Form all day?

Answer 1

The Battle Form has no duration

Though this ability has caused many discussions at paizo messageboards when first printed on Familiar Folio, due to how unclear the size adjustment should be applied and how it stacked (or not) with other polymorph effects, or what kind of action it used to shift back. The second time it got printed, on Ultimate Wilderness, all those things got reworded and clarified.

It is a polymorph effect, uses the default standard action for supernatural abilities, and should use the size adjustments from page 212 of the Core Rulebook. However, there is still no mention of a duration for that ability, meaning that it was never in error, it is meant to last for as long as you want.