I've never understand why people take such a clear issue against Jaina going to Boba to learn new fighting techniques. I'm not the biggest Travis fan but I think it was at least well explained. Jaina may have developed countless fighting techniques over the years but much of it was learnt either fighting alongside her brother or in the time when they were still close and would both share details and spare against one another, which means that if she fights him in the style she usually would he's going to be prepared for it and as he's picked up a host of talents during his five year travels that she doesn't know he's going to have all the upper ground.
The Mandalorians had never fought the Sith, had no experience combatting Dark Side users, and had lost every war when they went up against the Jedi.
If Fett had known Teras Kasi or had actually received some other form of training in combatting Jedi and Sith (what's good for one isn't always good for the other), maybe.
Instead Travis jammed her hand up her arse and pulled out "Mando mind-frak contradictory calm berzerker"... There have been plenty of techniques devised to limit a Jedi/Sith's ability to sense impending danger and their innate sight of a few seconds into the future, but obviously none of them were Mando enough or illogical enough for Travis to use.
If Travis hadn't completely changed Jaina's character and had Fett or other Mandalorians actually know any of the established techniques used to combat Jedi and Sith beyond pulling an excremental excuse for Mando superiority over Jedi in combat, it would have come off a thousand times better, and made her Mandos more bearable. Of course she didn't, because she didn't come up with them in the first place, so she wouldn't use something already existing for her
Mandos unless it was already Mandalorian in the first place.