The Total Amount of EXP you need to get to Clade Level 20 is 77900 Clade Experience Points

Number of Task Vendor (Reputation building) Parcels to be delivered to reach the final Clade Level (approximately 10 minutes on horse back between nearest cities) is 1558 Parcels, that is 260 hours of riding rounded up if you only travel between closest cities, and if we factor out being killed or distracted on the way. Each parcel delivery is 50 Clade EXP and 2 Reputation points for a specific nation. That is also a total of 3116 reputation points that you can spend on killing players and committing crimes in game. 3116 counts of crimes while being able to use the cities.

Zombies give you 2 clade EXP, you have to kill 38950 zombies to max out Clade

Scoundrels in Tindrem Sewers and Rat Tribesmen give you 12 Clade per kill, 6492 are needed to max out

Haven Bandits give you 16 Clade EXP per, you need to kill 4869 Haven Bandits to max out Clade
(This is a mindless grind and you can only get to level 8 in Haven but it is very easy you can do it with your eyes closed and it is very safe, I suggest you farm Bandit Dungeon in Haven until Clade 8 before you leave to make life easier in main game)

Regular Nave Bandits give you 22 Clade EXP per, 3541 kills needed to max out

Spear Sators in the Jungle give you 38 Clade EXP per, 2,050 are needed to max out
(You can't parry them, kite them on a horse and use the bow)

Claw Sators (without spear just using their hands) in the Jungle give you 26 Clade EXP per, 2,997 are needed to max out
(You can't parry them, kite them on a horse and use the bow)

Risar Soldiers give 45 Clade EXP per, 1732 Soldiers are needed to max out Clade

Minotaurs give 65 Clade EXP per, 1199 dead minotaurs are needed to max out Clade from level 0 You can solo them with a bow if you're good and get decent pay outs while doing so. Or you can tag team them

Unfortunately, regular animals do not give you any clade, nor does the PvP

You can use the Clade gains from various mobs I listed to calculate how many kills you have left to max out Clade from where you stand on your character or to reach specific levels, using the spreadsheet above.

For some reason after level 5 the amount of EXP you need to gain a level goes down instead of up but then it fixes itself at level 7.

I am not sure if this is an actual error or visual error. Never the less.

You can easily calculate how much EXP you will lose using the Spreadsheet above and something like the percentage calculator https://percentagecalculator.net/

For example, If you are level 16 going over to 17, add Accumulated EXP from level 15 in the table to the amount of EXP points you currently have in the current level EXP bar and then use the tool to see what 10% of that is. It is better to respec earlier than later as the amount of EXP you lose is more the higher you level up.

If you decide to Respec at level 20 you will lose 7790 Clade EXP points and will have to grind 'em all out again. That is slightly more than 1/3 of level 20. One Third of that level is 6,466 Clade EXP points. That is 174 Risars or 120 Minos

Now you know everything there is to know about Clade and what to anticipate and only you can tell if it is worth the grind