Would you please elaborate on your statement?
Please, call me by my first name, I start feeling old when people call me sir or mister
Anyway, in my experience, it is not really that difficult for an (strong) uke to resist an ikkyo by sheer force ("I'm not going to bend my elbow or go down"), or just roll out of it the moment it is applied, so when you apply it, it has to be near perfect. Now, achieving this near perfection is easy on a flexible uke who attacks relaxedly (is this a word?) with e.g. shomenuchi, but when you have an uke who comes at you full strenght and speed, you must be really good and fast if you want to a) take uke's centre and not get pushed into the mat and b) keep control of uke. In kaeshi-waza, ikkyo is the easiest to take over.
Most instructors/yudansha I speak with agree that ikkyo is one of the hardest techniques to do if you have an uke who is hellbent on getting out of it.