I feel like there are two broad styles of tanking: those who are conservative and those who are liberal
Conservative
Very conservative with the use of tank cooldowns. Attempt to hold onto as many tank cooldowns as possible for 'oh sh*t' moments in the raid so the healers are free to focus on everyone else. This however is at the cost of higher overall damage taken.
Liberal
Very liberal with the use of tanking cooldowns. Use them practically when they're off CD to reduce overall damage taken. This however is at the cost of potentially not having them if an 'oh sh*t' moment happens during an encounter.
I would say that I am more of a conservative tank. I like to save those CD's for when an attempt has taken a turn for the worse so they can stabilise the raid. I know that once that crisis is over they will have my back once again.