You will need servo extensions
Regardless of what type of flying you'll be doing it won't take you long before you run into a situation where your servo is too short to reach your receiver or flight controller. Servo extensions are the type of thing you should buy in bulk because you'll need them. A common size is 10CM (around 4"). You can buy them in 15CM or 30Cm which means they'll be close to 6" or 12"., I suggest buying these in bulk, one pack each (see below) and having them on hand because they will keep your plane out of the sky. You get a new plane, it shows up and 80% through the build when you realize your servos won't reach and you either have to pay too much or to source them somewhat locally or wait a month for them to show up from China.
The problem with servo extensions
Servo extensions work great, there are no problems until you take your eye off the ball. Sooner or later, if you don't check on them, they'll come apart. Sometimes they barely stop touching be look still connected. This means that you can potentially send a plane in the air with a control surface that doesn't work, or stops working in flight. I have experience landing a delta wing plane with only one working servo. I was fortunate that the control surface was close to neutral so that the plane was still able to do wide turns in one direction. With this, I had a very stressful landing, but the plane was fine.
Servo Safety Clips do one thing, the hold the connection between the male/female union together so that you don't have to worry about it. There is only one level of security I can think of that would be better. And that would be to cut off the male and female connectors and solder the ends together. Depending on how neat of a job you can do, you can hide the wring under a piece of heat shrink. There may be times due to space or weight limitations that you will need to do this. Sometimes you just need 5CM (2 inches) of wire and the extra two inches is in the way. Some people will cut and solder so that the wires are perfectly long enough.
There are even longer servo extensions which are fairly expensive because you really don't need them that often. If you're using a flight controller with FPV setups such as INAV a fairly common thing to do is push the micro receivers far away from other electronics. With a long servo extension, you can comfortably run the antenna away from other electronics.
Servo Extention Safety Clips
https://www.banggood.com/10pcs-Servo-Extension-Safety-Clip-Cable-Buckle-Fastener-Jointer-for-RC-Model-p-1341374.html?rmmds=myorder&ID=231&cur_warehouse=CN
20 Pieces/ 10 CM Servo Extention
https://www.banggood.com/20PCS-10cm-30-Core-Servo-Extension-Wire-Cable-Male-To-Male-For-FUTABA-JR-p-1620769.html?rmmds=search&cur_warehouse=CN
10 Piece /15CM Servo Extention
https://www.banggood.com/10-x-15cm-60-Cores-Servo-Extension-Wire-Cable-For-Futaba-JR-p-909171.html?rmmds=search&cur_warehouse=CN
10 Piece/30CM Servo Extention
https://www.banggood.com/10X-22AWG-60-Core-30cm-Male-to-Male-Futaba-Plug-Servo-Extension-Wire-Cable-Twisted-Cable-p-1102416.html?rmmds=search&cur_warehouse=CN
