Less is More?

[38BUBS]

Relatively new with Trimix ( total ED after radical prostatectomy 17 months ago, 74 years old had been using tadalafil successfully before surgery) did Bimix as test injection in docs office actually was with an APRN got maybe 50-60% erection so she said you need Trimix for the alprostadil, got Rx for 30-1-10 (alprostadil is 10) started 25 units got up to 50 units erections maybe a 70% gave her a call asking for higher concentration as would be more economical and inject less volume she sent Rx for 30-4-40.
She said start at 30 units I did 25 wife said 'like old times' I didn't think was much harder maybe 75% lasted about 90 minutes I was still looking for that 'Raging Hard-on' so went up to 30 units then 35 units paradoxically erection seemed to be less intense and the ache was mounting.
Decided to experiment did 8 units, onset of action took longer but erection was as good as the 25 units and barely any ache.
May try going to 5 units of the 30-4-40 and see.
Anyone else note less is more?