Personally I keep a tally of take-offs and landings on my PLOG and logbook, and find that if I'm doing much instructing I invariably end up demonstrating a few circuits in the course of the month, so it's little issue.
And if I'm not instructing, I'll usually be doing a bit of private flying and will often ensure an approach or a couple of circuits on the end of a sortie - but I appreciate that is an expensive luxury on the salaries many full time instructors earn.
That said it certainly can be an issue, particularly if you are mostly instructing existing qualified pilots, that you don't get much hands-on time. It hardly seems appropriate to log take-odds and landings where your student handled the controls.
G