Take screenshots on your mac from all your monitors and save them datewise. Use it together with cron.

take-screenshots.sh

#!/bin/bash

set -e

EXEC_PATH=/usr/sbin/screencapture

FOLDER=~/Pictures/journal/$(date +"%Y")-w$(date +%V)/$(date +'%Y-%m-%d')
mkdir -p $FOLDER
FILES=""
for screen in screen1 screen2
do
    FILES="$FILES $FOLDER/screenshot-$(date +'%H-%M')-$screen.jpg"
done
$EXEC_PATH -x $FILES

How to trigger screenshots every 30 minutes

Create the file and

chmod +x take-screenshots.sh

run

crontab -e

and add the following line

*/30 * * * * $HOME/Dropbox/scripts/take-screenshots.sh