Does conjuration dual casting perk have any effects on thralls?

The description of conjuration dual casting perk is dual casting a conjuration spell overcharges the spell, allowing it to last longer.

Since thralls are permanent, does that mean conjuration dual casting perk have no effects on thralls?

Solution 1:

All master level spells - be it Dead Thrall, Flame Thrall, a destruction spell or anything - are casted with two hands, and so 'dual-casting' does not apply. All also have a significant charge time.

This is irrelevant for conjuration master spells - as they are effectively permanent anyway (technically just a realllllllyyyy long time :P ) - but is important for the other schools. The lengthy cast time can often make them less effective than lower level spells and are generally only useful in certain scenarios due to their larger AoE or special effects. For base effects like pure damage, stun-lock, healing or illusion effects then dual-casted expert level spells are often more powerful.

Solution 2:

Thrall spells must be cast using both hands, you cannot allocate to the spell to just one hand.

Solution 3:

Because it can only be cast with 2 hands, there's no way to compare it's single-handed effectiveness. If the Dual-Casting perk were to, for example, double the duration of an atronach summon (Not sure what Conj DC does anyways, so just a rough guess,) maybe with the dual-casting perk, it would double the "permanent" (just very long) duration from 86313600 secs to 172627200 (even longer).