Okay well... Ummm Blast... I think you are confusing the bright patches Vs the Actual shiny/sparkly patches ... There are very Distinct differences between the two... Bright patches appear all the time... Shiny patches are what you're aiming for... TRUST ME... you will know one when you see it... and you'll be happy...
Patch Basics
There are three major types of patches... there are the normal patches... the brighter ones... and the shiny ones... Pokeradar pokemon can ONLY be found in the brighter patches... but otherwise every other pokemon that can be found, can be found in either of the patches...
You have to pick one of the two patches to start your chain with... and once you do, don't pick another patch type... like say, if you start your chain with a normal patch, don't switch to bright colored patch halfway through because it will mess up your chain like 99% of the time... you can get lucky and pull if off but it will be unlikely...
The other thing is that depending on the patch type will determine how efficiently you will be able to chain in some situations... like... if it's night time, you will want to try and go for the brighter patches to start with... that way you could see them better when you reset the radar... because normal patches are really hard to see sometimes... Also, bright colored patches are much easier to spot in sandstorm, hail, and rain areas... so you'll want to think about these things...
Also, there are subtle differences between patches even of the same type... some bright patches will look different than others and stuff... this can become important if you're trying to chain a very rare poke because it might break your chain.. most of the time though, if you pick the patch at the right distance, it won't matter... but if you want to play it safe, just learn to recognize the difference between each...