You don't need a hammer and a beaker to generate a tech point, no.  You have a form of inefficiency while any of the sliders is at less than 100%, because although you are still paying the same credits to maintain all those colony buildings, you are getting less from the ones that have less funding.

Each hammer or beaker costs 1bc to make, except for bonus hammers or beakers which you get because of your civ's abilities or from economic starbases, those cost half so 1bc for two (summed up under Bonus Production/Research on the budget).

What this means is that you will want to adjust the sliders according to your situation.  If you really don't need any new ships, you can set the military slider to zero.  If you're not building any new buildings, you can set the social slider to zero.  If for some reason you need to crank ships or buildings really fast, you can set the research slider very low or at zero.  You will never be able to get 100% efficiency across the board, but when you need it you can get maximum efficiency in one area.

Bear in mind that if you set a colony to produce no ships or buildings, the military and social funding it gets (Spending) will not actually be spent so you can cut back on outgoings that way too.

Well, in the later stages of the game, if you have lots of planets and lots of tiles to build income-generating buildings, you can get around the lowered efficiency by increasing the basic output.  To do this you can build economic starbases, or you can simply add more buildings (power plants can also help in some cases) or you can do both.  It really depends on whether your colonised planets are clustered (close enough that you can boost the production on several of them with one or more starbases) or scattered.

Each building may eat credits in maintenance though, which is why when I conquer planets I tend to demolish anything on the planet which does not fit in with my current plans, except recruiting centres and economic buildings which usually only cost 1bc apiece.  The initial colony on its own adds 10bc, and the basic production it generates can cost more than that.

I know that it seems odd to demolish a perfectly good factory or lab, but thing is, if I've got to the stage of invading a planet I already have a factory or lab somewhere else doing the same job.  I've now denied the enemy the use of those factories or labs, and on the off-chance that he re-conquers the planet, he has to waste time and credits rebuilding again.

One of the reasons for this is those basic labs or factories that get spammed onto all tiles as the AI notices empty tiles and thinks 'Need MOAR Research!' and 'Need MOAR Production!'  Then when it finally gets round to researching Xeno Economics practically all its tiles are full and it can barely squeeze in any Adv Market Centers.  Oops.

Giving the AI (and the human player too) less choices about what to build in the very beginning may mean a slower start overall, but one that lays a good foundation for the rest of the game.