Enchanted and rote block extensions

[InFerrumVeritas]

Because it isn't a spell as per the games mechanics but a spell-like effect. In the case of the item in question, it sounds like you need to balance between its strength and the number of uses you have available so you have most amount of flexibility with the item you can get for the cost you're willing to pay for it.

This isn't D&D.  There aren't any "spell-like effects."  It's a spell.  It may work differently, but it's a spell.

[Dr.FunLove]

EDITED: Agreed about distinction Mrmdubois!

[Mrmdubois]

I would actually say that it's an item created to cast a spell.

I don't see why this is a distinction that needs to be important though.

[GryMor]

Hears my personal analysis:
An enchanted item is the embodiment of casting a specific spell, with all parameters fixed at creation.
A practitioner, as a distinct spell, can extend one of their own Evocations (and presumably refresh the duration of a Thaumaturgical spell) if that Evocation has not yet ended (including if it would end at the end of their turn).
When dealing with a spell created via an enchanted item, for many purposes, the enchanted item is the caster of the spell.
The practitioner wanting to extend it isn't the caster, and so can't extend it directly.
The enchanted item can only cast a singular fixed spell per slot.

Therefore, the only way to extend an enchanted items spell is by using a two slot enchanted item, with one slot being the base spell and the other spell being the extension of the first spell.

YMMV, if I were actually running a game, I'd likely let someone capable of reliably casting the spell from an enchanted item they made extend it.

[Tedronai]

Hears my personal analysis:
An enchanted item is the embodiment of casting a specific spell, with all parameters fixed at creation.
A practitioner, as a distinct spell, can extend one of their own Evocations (and presumably refresh the duration of a Thaumaturgical spell) if that Evocation has not yet ended (including if it would end at the end of their turn).
When dealing with a spell created via an enchanted item, for many purposes, the enchanted item is the caster of the spell.
The practitioner wanting to extend it isn't the caster, and so can't extend it directly.
The enchanted item can only cast a singular fixed spell per slot.

This is a wonderfully internally-consistent rationalisation, so long as everyone remembers that it is just that.
It does not have sufficient backing in the rules to be said to be anything more than a house-rule answering a question left unclear by the rules.
That said, any game that I ran would likely implement a houserule to similar effect for all cases where a player did not present extraordinary narrative justification otherwise.