Online I alert every bid that is artificial or that the ops are not likely to understand.Although here in Australia we are banned by law from alerting bids over 3NT,cue bids of ops' suit and doubles as these are considered as self alerting.I was playing here the other day with my reg partner and we had a sequence of bids that we alerted and were asked "Is this a learner's table"because of all the explainations :D .I know that at at least 1 of our local clubs we are known as "The Knock Knock Twins"due to our frequent alerts.We also offer to explain the entire auction before the ops lead(this is also a requirement in Ozzie bridge...but rarely adhered to). So keep alerting everthing and when in doubt alert. As an aside why do people here press the alert button and then not fill in the box?It just means more wasted time asking and waiting for answer.