yup, on average every 10 mins - could be a couple an hour or a dozen an hour :-)

difficulty changes up or down every 2,016 blocks. 2016 * 10 mins = 20,160 mins = ~2 weeks
https://coin.dance/blocks#blockDetails
https://www.xbt.eu/

block reward halves every 210,000 blocks
http://www.bitcoinblockhalf.com/