R9 could or couldn't be included.. Its presence depends on how much regulated is +24V..
(e.g. in case of +24v taken from a truck battery, it should be useless..)
R9 & C11 form low pass filter of about 34Hz cut off frequency while there is a voltage drop across R9 (is set in series with +12V) proportional to current draw by load..
e.g. in case of a 1k2 load resistance, between +12V & GND, there is a 10mA current flowing across it.. That current also flows through R9 resulting into 1V voltage drop..
If you wish to preserve 34Hz cut off frequency, it should be better to make R9 value 10R (ten times smaller) and make C11 value 470μF (10 times bigger)
P.S.
Same stand for R12 / C12..