B mode on the TCH will bost regen if your speed is under roughly 18mph. Much over that and the ICE is spun up to assist with braking, regardless of the batteries SOC. The FEH in L will not spin up the ICE unless you are over 40mph or the SOC is full.
You are better off to conserve momentum when possible. Now if you know you will need to stop or slow down significantly, lightly braking should give you more regen than coasting and then braking harder.
You may have heard the expression "drive with the load". Essentially that means to let your speed bleed off as you go up a hill, and let it build some as you go down. You are letting your momentum carry you over the hill, avoiding heavy use of the ICE. Obviously you don't want to be a rolling roadblock as you crest every hill. But allowing your speed to drop 5mph or so as you crest a hill, and go 5mph or so over your desired speed when going back down will boost your mpg.
