You don't need to use that high percentage for each flavor, no. I like real flavors just fine and at way lower percentages than that, so keep in mind it is just a suggestion, although it certainly might be the "right" percentage for some palates, especially if coming from storebought.
My recommendation would be to mix up small tester mixes of single flavors for at least SOME of the flavors. Try on the low side, do some steeping and tasting along the way, and start LOWER than higher, it's a lot easier to add flavor than it is to dilute down (although I have most certainly done BOTH on occasion.)
While an "across the board" suggestion for flavors even from the same manufacturer is near impossible, well, it should start to give you a "
sense" for the flavoring and how it works for you. I did that a bunch early on and steeped, and mixed flavors IN my
tank (not the same as a recipe but it gave me a sense of what COULD work with what) as I got started. I wrote down EVERYTHING. It was a slower DIY start for me, but it did give me a sense of my flavors before I began embarking on more complicated mixes..
Also, if a mix fails, don't toss it, try to fix it! I have learned more about DIY by doing that than by ANY of my "excellently lucky out of the gate" DIY mixes. Fixing a flavor is a real challenge, and you have nothing to lose besides some time, creativity, and really learning about how dilution works. Best of luck,
Anna