Honestly, and there may be a bit of salt involved with this opinion: I think people are just freaking incompetent. That seems to be the reason 90% of the time why they are not using the special when it's obviously the smartest and most useful thing to do. There are SOOO many people on Profreshional rank who don't seem to even have a clue or the fighting skill to deserve that rank. It seems to be way too easy to get carried up there right now. I sometimes catch myself having the very egoistic though of tying SR to your Solo Rank. Which doesn't hold sense, of course, as SR is supposed to have its own rank. I just find this system to be too forgiving.
A little overview on what I think of the specials and my experience of what people do not do with them when they should do it.
Stingray:
I start with the most enraging one. Atleast 70% of the Profreshional playerbase does not seem to know that the stingray is ABSOLUTELY required to live through Mothership waves smoothly. You go back and launch it once the ship comes in. While you damage it, you can even destroy approaching enemies to farm eggs.
If you don't do it, you'll risk your other teammates investing their specials (inkjet, splashdown) because you are not doing your freaking JOB.
The second thing barely anyone seems to notice is that the Stingray can revive teammates ALL across the map. Only a handful of players seem to grasp the art of being the last man standing, launching the ray and saving the day by pulling off a double/triple revive.
Bomb Rush:
This is very situational. And it's more useful than you think. It can be a great asset for turfing area or reviving teammates that died close to each other. It's also great to hold off incoming enemies in glowfly waves. What peole do wrong a lot is just launch it for no reason because they think "its crap anyway" and that "i could use it in wave 1 to turf". NO!
Inkjet:
The inket is just great. At nearly everything. USE it! I can't count what you can do. You can take down any large amount of bosses, revive teammates, use it to stay alive safely, etc. All you have to do is "feel" when it's right to use it. Spoiler alert: It's almost never right to use it in wave 1. If your team struggles in wave 1, use your skill. It's very likely that you'll need your special at a later point if wave 1 already overburdens you guys.
Splashdown:
Splashdown is what it is in SR. It's an emergency button. You can take down enemies surrounding you, You can revive nearby teammates. You can use it to stall. The problem with this one is that people use it too early a lot. Be mindful that you only have 2 panic buttons. Don't waste them.
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It's good I got the message out there now. There is so much more that lately ruins my fun in SR. I start to have the feeling that it is not only related to ranking up being so easy. I have the feeling kids are starting to use that cheat tool to edit their SR rank. Because it is capable of doing that...