I probe ALL jump points with scout pinnaces. Either 250 ton ones that are really cheap, and use the minimum ship sensors to check out planets, or 500 ton ones with 3 HS sensors.
Scout pinnaces have 30-60 billion km range, a .5 hs engineering system.
Fleet scouts are much shorter endurance, with boosted engines and no jump drive or engineering system, and are used for tactical scouting, not strategic.
Once I get x.33 reduced sized launchers, I build a pinnace with a launcher, minimum fire control, and a magazine full of sensor missiles of various types.
A lot of AIs don't shoot at buoys or sensor missiles, so you can occasionally get a fix on them, and then get an idea of their passive sensor range when they start moving on detection of your battle fleet. I like the game of trying to figure out the enemy's capacities before actually fighting them.