As long as the scripts take less then 3 minutes this should fire every 3 minutes..while :
do
sleep 180 & # Run sleep in the background
/path/to/dir/test1
/path/to/dir/test2
wait...
Instead of joining 2 scripts, you can write another caller script which will invoke test1 & test2 every 3 minutes:-
#!/bin/ksh
while (true) # Infinite while loop
do
/etc/test1 #...