A referendum for assessing political parties' performance?

One term usually constitutes five years in power for any elected government. However, those five years can be undisturbed and unchecked by the population, despite the fact that our political sphere may be plunged into chaos. Why must the public wait for Parliament to decide on a snap election? Why must there initially even be an election at all with all its complexities (e.g. competing self-interests, manifestos and intense campaigns)? Surely it would be better if the election seemed like a last resort? Instead, maybe the British public should vote on whether they would like a party to remain in power midway through its term (i.e. 2.5 years into the party's tenure). This should be written into law, with a punishment for a majority expressing disapproval.

For example, Cameron won the majority in 2015. What if the Conservatives had been faced with the hypothetical, legally enforced referendum in June 2017 (with Theresa May at the helm at this point), with people responding to a question along the lines of the following: 'Do you believe the Party has successfully fulfilled its duty by keeping the promises that they made when they were elected? Vote "Yes" or "No".'

I feel as though more people would have voted 'No' (e.g. 69% vote 'No' and 31% vote 'Yes'). As a result, the punishment would be a snap election (as the law would state in this hypothetical scenario). I also feel as though this particular election would have to be played by new rules. A different voting system would be used for this type of election (i.e. the compulsory snap election for a party failing to gain the trust of the people, which would have been made clear by the midway referendum). I think that this election could use something like RP. However, other voting systems could also be up for debate. I think that FPTP could stay for normal general elections, but these ones should give the people a chance to vote for their new party differently. I feel as though this second chance should definitely do everything it can to make people's votes count and yield a result that creates the clearest, cleanest, most representative picture of the electorate's decision.

Another idea is that losing this referendum would immediately put the opposition party into power, although I feel that this may be slightly undemocratic.

I think this would put pressure on politicians to perform consistently as there would be no way of avoiding the people's wrath come the obligatory referendum two-and-a-half years into their rule. People are not likely to forget a party's failures.

I think that people deciding whether they like the government or not isn't too complex a decision, unlike Brexit. You either think the government are trustworthy and are implementing the policies that got them to where they are in the first place, or they are not. You keep the politicians' feet near the fire. This referendum would also just be one party in the matter. The only opposition they have is the people. It's not a political match between two campaigning groups vying for power. All the government have to do to pass this checkup is do their job. It is merely the green light given by the people for the second half of their tenure.

(I'm just a novice and getting into politics. I don't know if this idea has been discussed before, and I don't if it's even a good one. I'd like to see your thoughts on it, and maybe over time, we can make amendments to it that make it more viable. Or, we can just trash it (which let's face it, with my inexperience in debating politics, would probably happen).)

Sounds like a good way to create more or less perpetual uncertainty, and block governments from doing anything longer-term... and it'd also dig up the nasty, divisive, misleading election campaign stuff every couple of years (minimum, guaranteed).

Not for me.

So a general election every 2 years? Not a chance.

It wouldn't be a general election every two-and-a-half years if a majority of the electorate agreed that the party had performed well halfway through its term. Is a referendum that similar? Sorry, I'm really exposing my ignorance a bit here.

Oh no.
The last thing that the UK needs is to start scheduling more referendums!