Ever hear of the 80/20 rule?
You get 80% of the results form 20% of what you are donig. I.E. the time you spent doing the 5x5 is the 20% and will give you the majority of your results.
Regarding the other stuff (the 80%), remember, that is only getting you 20% of your results (give or take), I would limit the assistance exercises to 2 (maybe 3) exercises that you really like and you know work well for your body. Then with less exercises, you do more sets for those 2 exercises rather than doing 6 or 7 assistance exercises. Also, to reinforce technique, you could also add in some light/explosive work for a previously worked 5x5, so for example, on back/bicep day, you could do:
Deadlift: 5 x 5
Wide grip pulldowns (normal grip pulldowns): 6 sets - an increase in sets
Neutral grip machine row (reverse grip machine row): 6 sets - an increase in sets
Bench Press: 5 x 3 reps at 75% of the weight you used on Monday (so if you did 200 for 5 sets of 5, than on Tuesday you would do 5 sets of 3 at 150, paused on the chest and EXPLOSIVE)
If you must, you could easily throw in a few sets of curls between set of bench press.
I personally think this would work much better.
James 1:16-17 ESV
Do not be deceived, my beloved brothers. Every good gift and every perfect gift is from above, coming down from the Father of lights
With God's help...Mens sana in corpore sano