So am I, so I find using a £10 hack bike painted by a blind man using a yard broom and secured by a £10 padlock & chain achieves exactly the same result as your 3 D-locks without me needing to carry several pounds in weight of extra steel around. Also, if a determined thief armed with a grinder does take a fancy to your bike, not only have you lost the bike but also the cost of the expensive locks that will get destroyed. The best way not to get robbed is don't go around with anything worth nicking.
My total theft risk exposure out on the street is probably less that one of your locks, never mind the bike. I often don't even carry any lock on my better bikes, because I simply will not leave them unattended out of my sight. There are bikes for riding from door to door and there are bikes for local utility transport and leaving on the street. Different bikes for different levels of risk. The only sort of person who would want to nick one of my hack bikes is a drunk who's just staggered out of the pub or has missed the last bus, and is unlikely to be carrying thieving tools. A thief hunting for a quick sale for ready cash isn't going to look twice at what I leave unattended.