Okay, here's an interesting idea: what happens when Homura sticks one of our complex Grief constructs into her shield? While it's obvious that, even if it remains intact when being put inside of her shield, if she removes it from her shield when further than 100 meters away from Sabrina, it will break apart, if it
does remain intact if she brings it out when within 100 meters of us, that has all sorts of potential uses.
For example: let's say we may some kind of personal shield generator or flight pack. Homura sticks it into her shield. Then, while fighting Walpurgisnacht, Homura, while staying within 100 meters of us, takes out the flight pack and equips it, giving her the ability to fly and maneuver, or have a shield generator for added protection. Beyond that, it's a way to save us time making the constructs if we don't want to carry around things all the time that scream
Witch! to megucas's senses.
We should also ask Homura if she's ever tried sticking a Soul Gem into her shield before, and if it's possible to stick bodies in there as well. If she's never thought of the possibility, and it works, then we could give her some reassurance that, even if the worst should happen and this loop fails, she'll have a new way forward, potentially bringing Sabrina or others along with her.
Well I mean yeah, solo Witch hunts are dangerous, but that's mostly because fighting Witches is dangerous, not because they're solo.
Magical Girls teaming up is normally not done considering resources and whatnot. The groups in Mitakihara and Asunaro are actually out of the norm.
Solo Witch hunts usually are the norm.
Er, magical girls teaming up
is the norm. Practically everywhere we've gone, we've seen magical girls working in teams of at least two. Many of the teams we've seen have five or more.
Also, fighting Witches solo is a lot more dangerous than fighting them in teams, for a lot of reasons. Having someone always watching your back, always offering a second opinion when needed, always ready to bail you out of a bad situation, and always dividing the enemy's focus. Not to mention the fact that having multiple powers and skill-sets means that you're a lot less likely to be screwed by encountering a Witch whose abilities counter yours.
There's lots of evidence showing why solo Witch hunting is a lot more dangerous. Mami's canonical death via Charlotte, despite being an extremely skilled veteran. Kyouko's near-death at our first meeting, only saved by a last-second intervention by Sabrina and Yuma. The dead teammate of the two girls immigrating into Mitakihara tomorrow. One of the first Witches Mami fought nearly killed her, too, and she only managed to escape with injuries. In the end, all it takes is getting caught off guard once, and without someone to back you up, you might not be able to recover before things get worse and worse, until you're killed. Since every Witch is different, and every Barrier is different, getting caught off guard is a constant risk.
Experience helps a lot, but no one is infallible. Without some kind of truly broken power (like timestop or Grief control), all it takes is not being cautious enough at the wrong moment.
As for Sayaka being able to call Homura for help--let's not forget that it's entirely possible to become body-killed in an instant, or for an attack to target her soul gem, killing her instantly. And it's not like Sayaka is perfect. In the heat of the moment, she might forget about calling Homura telepathically until it's too late to convey the message.
We trust Homura to do solo Witch hunts because she has the right combination of qualities: her power is versatile and broken as hell, she's very experienced, she's always vigilant and cautious, and she's got a pocket dimension full of tools for many situations and threats. Hell, even against antimagic, she's still extremely dangerous, as Kirika and Oriko found out the hard way.
Likewise, Sabrina is a safe bet for solo Witch hunts because her power is just
that broken and perfectly suited for hunting Witches. She can sense everything around her at all times, from the Familiars to everything in the Barrier itself. She can fly, protect herself from all angles at a moment's notice, negate and destroy the environment of the Barrier itself, and her power can literally disintegrate Witches directly by just taking control of the Grief their bodies are comprised of. Thanks to her flight, she can still be highly mobile even if she loses her legs, and she can still fight highly effectively without arms. Antimagic is still a problem, as is timestop, but it stands to reason that Witches with offensive antimagic or timestop capabilities are either extremely rare or unheard of, and no amount of teammates could do anything about timestopping Witches unless they're precogs.