Watch all repositories that you have read/write/admin access to.

github-watch-all.py

import requests

API = 'https://api.github.com'
session = requests.Session()
session.auth = ('YourUsername', 'YourPassword')

def repos():
  page = 0
  while True:
    repos = session.get(API + '/user/repos?page={}'.format(page)).json()
    if not repos:
      break
    yield from repos
    page += 1

def subscribe(owner, repo):
  url = API + '/repos/{}/{}/subscription'.format(owner, name)
  return session.put(url, json={'subscribed': 'true'}).json()

def main():
  for repo in repos():
    owner, name = repo['owner']['login'], repo['name']
    resp = subscribe(owner, name)
    if not resp['subscribed']:
      print('error: unable to subscribe to {}/{}'.format(owner, name))
    else:
      print('subscribed to {}/{}'.format(owner, name))

if __name__ == '__main__':
  main()