don't ask me the science behind it i don't know ,,, but for venison i do not add fat or pork belly etc and juicy and fine!
but for sausages yes need it,
if other burgers from pheasant or rabbit i add 20% fat i think it need sit
you can buy packs of seasoning alone or seasoning and rusk , buy rusk on its own etc ...just add water to these mix and make your burger
i prefer to make my own
as for rusk or no rusk .... amounts i do them in, usually 50x plus at a time or more you need something to hold them together .... i coarse mince for burgers and i fine mince for sausages , then sausages once mixed with rusk and seasoning of choice i mince again till the mix is literally like sh1t on a blanket ..... think charcutier guys call it the primary bind.
as for flavours you yes i agree a basic seasoned salt & pepper burger you get flavour of the venison!
but equally once your eating a lot of it and want variety then adding sauces and flavourings your imagination is the limit
venison & brown sauce
venison with cranberry jelly
venison with grated cheese & spring onions
etc etc
base seasoning i always go 2% salt 1% ground black pepper
start lower on salt till find point you like it ...some salt is saltier than others
i started buying BBQ rubs / seasoning from Angus & Oink as i love their stuff and their Jamaican jerk seasoning in rabbit burgers was amazing i for go the base seasoning and just use that at approx 3% that's it
they have a flavour profiles from all other the world ....used their shawarma seasoning thru lamb for a middle eastern donor type burger etc
some folk will like your burger some won't ....everybody tastes are different and there is no right or wrong... its what you like
and experimenting is half fun.... take notes, log your efforts because when you hit the daddy that you think is the bomb...you'll have the recipe noted otherwise you will forget it!
enjoy
Paul