In #16116 some thoughts where shared about RTT_FREQUENCY.
maybe a sensible default should be choosen.
there are two mainly used ~32kHz and 1Hz (non 1000Hz)
grep “define.*RTT_FREQUENCY” showed
32k 19 1 12 Max 3 (iotlab is one) at a first glace these are 32kibiHz 16k 3 1024 2 4096 1 (nucleo-f413zh)
there are 5 rtt users in sys/Makefile.dep
ztimer (likes to put msec on rtt) posix_sleep ztimer_msec gomach (somthing about 300ms supercycles) lwmac (calculates in 2ms - 300ms range) sklad ztimer_msec
since not every RTT is configurable a sane default should be choosen i vote for ~32kHz