Gardening: When do I need to trim my trees?

My sequoia trees were planted in 1997. The last time they were trimmed was 2013. What do you recommend for a trimming time table? Marlene de Valera, Simi Valley
I would not think in terms of a strict schedule for trimming any type of tree but rather proceed with trimming on an as-needed basis.
Reasons to trim or prune sequoia trees include dead or broken branches, branches growing over your roof or into other trees or utility wires, or too much shade for your liking.
Some arb