I strongly support making the bonus every tick! Hell, everything should be tick based, and I think espionage is the only remaining cycle based effect? Right now it’s still very important to be online for the espionage tick, and in the end game you get more science from espionage than science labs.
A few ideas were:
You get an espionage hit every cycle at a random tick. So every cycle you know you will get an espionage hit, but you don’t know which tick it will happen on. I’m not sure I like this idea, but it’s worth considering.
Espionage triggers every turn but applies to a completely random research. Even undo the nerf and make it how it was with +100% scanned science. The purpose of espionage would then be to give bonuses to empires who decide to work outside a team. If you are playing solo you invest in scanning and experimentation.
Tie the science points gained the the research the other empire is better at? Not sure about that. Could be interesting.
Tie it to fleets. The idea is fleets are expensive, so if you make the espionage bonus scale with fleets it will be somewhat self limiting. If you also make it require strategically positioning your fleets for best effect then it seems good. You get espionage bonuses for every system which has scanning range on a fleet. The bonus is multiplied by the fleets. So the bonus is every fleet which is scanning range of every enemy star system. This makes scanning tech bad because you are giving away tech, but it also gives advantage to underdog.
I like the idea of using fleets to strategically leach science from your neighbours but maybe not so much the enemy-scanning mechanic. Maybe you just keep espionage exactly how it is now, but it only works from stationary fleets. If a star has multiple stationary fleets then the bonus is multiplied. But… you are not using your fleets, and they need to be near your borders where they are most useless since they are not transporting ships.