depends on the email's subject. i usually check my email inboxes regularly (every 3-4 hours) and decide then when can I deal with emails, depending on the urgency of the topic.
I use to check it regularly and decide to deal with them depending on the subject of the e-mail except during weekends. Unless I am expecting some important e-mail I try not to check office mailbox on Saturday and Sunday to give some time to personal life.
Though I am 69 years old,I try my best to reply within few minutes,provided internet is working.I am an Indian working as Professor of Veterinary Public Health, Addis Ababa University.Sometime,we face severe problem of electricity and internet.Then,i am unable to reply.It is very difficult to predict. for future.Today,internet is fast ,so I am replying you immediately.
I do not have facility of internet at my residence.Sometimes,I go to city to check my email.Moreover,due to growing age,I am loosing interest in all these things.